It actually worked!
I could have sworn I posted when this date seed was planted, but I can't seem to find it to link to, so maybe I imagined it. Anyway, bottom line, some archaeologists found a 2,000 year old date palm seed at Masada, in Israel, planted it, and unbelievably, a couple years later, it's growing and doing fine:
Researchers Resurrect Extinct Judean Date Palm Tree from 2,000 Year Old Seed (AAAS)
The Judean date palm (a variety of Phoenix dactylifera), of which this "Methuselah" is perhaps the last remaining vestige, was once a staple crop of ancient Palestine, at one point existing in vast, towering forests along the Jordan River valley. Date palm culture declined after the arrival of Roman occupation (the Romans had a lot to do with this by preventing the Jews from propagating it), and the Judean date palm appears to have been wiped out entirely by about the sixth century A.D. Modern date palms, still a major industry in Israel, are from imported stock.
Delving into the highly reliable realm of information gathered from anonymous somebodies on internet forums that blogs so often deal in, I also found this post on PalmTalk, which references a genetic study suggesting that the plant bears little resemblance to modern palms, with only a 13% similarity to an ancient Egyptian cultivar (search for "13% similarity" or go maybe a third of the way down the page to a post by 'rubyz'). Another incredibly reliable source, Wikipedia, states that the Egyptian cultivar is Hayany, and that it is a 13% dissimilarity. Who knows. Probably it's at least kind of related to something. Still, whatever its DNA says, it's still pretty cool.