Bah... I know I'm shooting Canon now, but I had to come in and brag about this. I know the Sony people here better than I know the Canon people yet.
You guys have seen me drooling over this lens for 6 months, and not quit talking about it. It was actually the money I saved up to buy this for my A300 that I spent on my Rebel XS, which I then sold to buy this in Canon mount.
So I got the Tamron 17-50 f/2.8 earlier this week from Best Buy. Most of the BBs in this area don't carry as much stuff as the one in Cary (the one by my house certainly doesn't) but I noticed a couple of months ago (when I was looking for the Sony mount 17-50) that the BB in Cary had the Canon mount on clearance. So I went back to check and all they had left was the floor model, but it had barely been touched. Most people shopping for this quality of lens don't shop at Best Buy. So they packed it up in the box for me and sold it for $350. Sweet deal, sweet lens. I had my last finals this week (as of today I am finally done with school for good!) so I haven't shot with it a bunch, but initial test show it has the same sharpness everyone talks about. Sadly on Canon I don't have IS, and the AF is through a super-noisy internal motor, but it does focus quickly, and between the wide aperture and high ISO I can shoot, I expect to be able to do a decent job of combating shake.
If you are shooting Sony and don't have this lens, go get it.
Now back to your regularly scheduled foruming-in-the-correct-forum. ;)