Meat potlucks (whether one table, two tables, or as we'll see below, four tables) are rare in general in Jewish communities that observe any form of kashrut. This is in part because keeping it veg makes it much easier to negotiate among different standards of kashrut, and in part (even in communities with a more uniform standard of kashrut) for cultural reasons -- the meat crowd doesn't tend to overlap much with the potluck crowd. There are some exceptions: KOE has meat potlucks on occasion. I've never been to one, so I can't report on what these are like.
For the most part, my Jewish scene is vegetarian, not because everyone (or, perhaps, even a majority of people) in it is vegetarian, but because vegetarianism is a social norm (as kashrut is in many contexts). I'm a flexitarian, meaning that I'm not really a vegetarian (though I am a meat reductionist), but I live a vegetarian lifestyle most of the time. I keep a dairy kitchen at home, and only eat kosher meat, and am rarely in an environment where kosher meat is present (since most people I hang out with either don't eat meat or eat non-kosher meat), so I end up eating meat very rarely (though I still eat turkey when I go to the old country for Thanksgiving, and won't say no to the occasional shwarma when I get to Israel), and I'm fine with that. Vegetarianism is enough of a norm in my world (and I am effectively vegetarian when in non-kosher contexts) that people are always surprised to find out that I'm not vegetarian.
So this is the context in which the two-table meat potluck arose. I think the organizer was trying to make the point that the overlap between the meat crowd (that is, people who would eat meat, regardless of how often they actually do) and the potluck crowd is larger than we are often led to believe.
This is how the two tables were defined in the invitation:
Table 1: Non-dairy vegetarian food. Eggs and fish with fins and scales are OK, but please be careful that there are no dairy ingredients.
Table 2: Non-dairy vegetarian or meat food in which all ingredients are marked with a hechsher (more than just "K"), prepared on pareve or meat dishes in a kosher kitchen that uses only hechshered products.
A number of observations just about the theory (before we even get into the implementation):
- This is, of course, not the only way a two-table meat potluck might have been envisioned. Other variations might include non-kosher meat on Table 1, or kosher meat prepared on any dishes on Table 1.
- People with all-hechsher dairy kitchens, who ordinarily prepare food for Table 2, must cook for Table 1 this time (even though it's conceivable that some of them might not eat from Table 1).
- Unlike in the standard two-table system, there are now people (vegetarians who aren't concerned about dishes or hechshers) who will eat only from Table 1 and not from Table 2. In the standard two-table system, there are people who will eat from both tables, and people who will eat from only Table 2.
- There are also people (vegetarians who are concerned about dishes and/or hechshers) who can't eat from either table.
- Those last two points aren't precisely true, since the vegetarian items on Table 2 should be self-evident enough that vegetarians can distinguish them from the meat items. (Jews who keep kosher don't generally put clandestine meat in their cooking the way some cuisines do.)
- Stringencies about kosher dishes and utensils are based on the presumption that hot (in temperature or flavor) food absorbs the essence of meat or milk from the dishes. Are there any vegetarians who take this presumption seriously enough that they won't eat anything that has been cooked on fleishig dishes?
- Because it was dark out and hard to see precisely what was in each food item, someone suggested that, for the benefit of vegetarians (as discussed above), Table 2 be separated into two tables: Table 2 (for vegetarian items) and Table 3 (for meat items). And it was so.
- After all that, Table 3 only had three things on it. So this meat potluck didn't actually have so much meat at it. I guess this isn't so surprising, since not many people in this crowd (even the meat-eaters) have kosher fleishig (or bipolar) kitchens -- a lot of people have either milchig kitchens or non-kosher kitchens. I suppose I could have picked something up at Gan Asia, but I didn't think of it; instead I was lame and brought fruit. (Initially I split the fruit up between Tables 1 and 2, since there was no "common denominator" table. After Table 2 was split into 2 and 3, I put all the fruit on Table 2, because the new Table 2 was now a common denominator.)
- And then someone showed up who had heard about the potluck indirectly and hadn't gotten the message about what made this potluck different from all other potlucks, so this person brought something dairy! So they had to create a Table 0 (the numbering of the additional tables was based on their spatial positioning), from which the vegetarians happily ate. I don't know if anyone ate from both Tables 0 and 3, but that's their business.
UPDATE: I should clarify that "common denominator" remark, lest I appear to be using Stage 1 discourse. I meant it in the "universal donor" sense. One-table potlucks (operating in some sort of framework of kashrut) generally have a "universal donor" table. Conventional two-table potlucks have a "universal recipient" table (that is, universal in regard to whose kitchens it can receive food from, though not necessarily universal in regard to what food it can receive) and a "universal donor" table. These are the most abstract and idealized definitions of Table 1 and Table 2. Any specifics about hechshers, etc., are just the implementations of those idealized definitions, and are dependent on the range of practices in the specific community. This is why no more than two tables are necessary, and why questions like "What about cheese?" are a distraction (except when a particular community is determining its implementation of "universal donor" and "universal recipient"). This fleishig two-table potluck (as originally conceived) was unusual in that no table was a universal donor. Though I suppose if we're looking at this on a theoretical level, then it's not so unusual, since any food allergy could be isomorphic to vegetarianism.
UPDATE 2: ASL points out that he sent out the Evite only three days before the event, and that lots of the people who replied no are people who would have brought meat. So as long as we're trafficking in cultural stereotypes (cf. the reference above to the overlap, or lack thereof, between the meat crowd and the potluck crowd), I wonder if there is a correlation between eating meat and making Shabbat plans more than three days in advance.