This article in Zeek by Rabbi Arthur Waskow and Victoria Finlay actually manages to include both of my top two Tu Bishvat pet peeves in the opening graf:
The #1 pet peeve is, of course, "Tu B'Shvat". (I feel slightly bad that I'm helping out this spelling's PageRank by printing it.) The #2 is the analogy to April 15, a common analogy in explaining the "four new years" to Americans. Why April 15?
Wouldn't it seem strange if you discovered that April 15, Income Tax Day, had been transformed into a festival for celebrating God's reemergence? Yet that is what the Kabbalists of Safed did in the sixteenth century when they recreated Tu B'Shvat, which Jews will celebrate this year on February 8-9.
Tu B'Shvat, the full moon of mid-winter, had been important only in Holy Temple days as a tax day. It marked the end of the "fiscal year" for trees, the key capital investment in an agricultural society. Fruit that appeared before that date was taxed for the previous year; fruit that appeared later, for the following year.
This is an accurate description of the original function of Tu Bishvat (and 1 Elul, for livestock). And we do indeed have a date that serves as the end of the fiscal year for individual income taxes in the United States, but it's not April 15; it's December 31! April 15 is merely the deadline to file a tax return. So why does this flawed analogy get perpetuated? Because people hear "April 15" and think "taxes", which is not necessarily people's primary association when they hear "December 31" or "January 1". (Also perhaps because saying that one new year marks the beginning of the year and another one is like January 1 doesn't help elucidate the concept of multiple new years.) But that doesn't make it correct.
If we were to identify a date on the Hebrew calendar that would be a more accurate counterpart to April 15 (the deadline to pay taxes), then (according to Mishnah Ma'aser Sheini 5:6), it might be the 7th day of Pesach, which falls this year on... April 15!!! (Yes, I know this isn't the right year in the 7-year cycle for this correspondence to work out perfectly. Oh well.)