Picked up the Tamron SP 70-300mm F/4-5.6 Di VC USD today.  I've been looking (and drooling over) at this lens for awhile now.  Its won Tamron quite a few rewards also.  I've just played with it briefly, but I'm impressed so far.  I compared it with my kit zoom lens and my low end Tamron and I have to say, I love it!  As Ferris would say, "Its so choice!"
Given the f/4, I probably won't use it that much in low light, but I can't wait to try it out on some wildlife.  I think I'll be giving my coworkers a reason to make fun of me by going into work on my day off Monday to shoot some pics. 
I'll try to set up and do a side by side comparison if anyone is interested.

would love to see some of the results, i am looking at upgrading my kit len and im not to sure what i want yet, this should help a bit with my choice