I love the two pages of people band-wagoning on the "squeezing is bad" train... without any actual input or evidence or anything. Thats why science will always win the day.. because so many people are ignorant!
The earth was flat one day... and you would be put to death for heresy if you objected. Don't beleive the hype!
I don't think I've seen conclusive evidence for either side (might have missed it), and I'm not going to trust someone tasting beer with their tongue for tannin detection. It looks like someone in chemistry could easily do a KOH test for the presence of tannins in wort (see wikipedia below).
According to wikipedia, tannin extraction can be accelerated with increased temperature and pH, but they're still water soluble, and they'd still probably leach out if they sat in room temperature water long enough.
http://en.wikipedia.org/wiki/Tannin#cite_note-Hagerman1988-26
For me, I don't think there's enough tannin on my grains to care if it all ends up in my beer. Off to squeeze my bag...