this is SWEET!
I was cruising the net the other night and happened upon Sigma's site, where I noticed the "outlet" link. They had a 17-70 OS HSM for sale, for $349.00. I had the older version last summer, and liked it pretty well, but...meh...it didn't trigger the right response, so I sold it.
I've been watching and waiting for a chance to get my hands on an OS version, and took the plunge. I've got a couple other Sigma's that I use a lot, and like really well.
This lens is "Da Bomb"! I'll do a proper MA test tomorrow, but it seems as if it's focusing beautifully with my 50D. The box (original retail box) looks unused, all components look pristine. Might be an overstock? Anyway, I'm highly pleased with it. It's a very useful focal range, and the pictures seem crisp enough to challenge my 24-105. Stand by for further information...