Sigma 17-70mm lens for digital SLRs: Digital Photography Review
This is a replacement for the standard lens that ships with Nikon or Canon lower end dSLRs. I suspect it will cost @ $300 or so, but there's no price data yet.
It's for APS-C, not full-frame dSLRs (Canon owns the full frame dSLR market).
I don't know how the 3x4 (consumer cameras mostly) vs. 2x3 (film and almost all dSLR) ratio-wars will turn out, but I think the full frame 35mm sized sensor will become very rare. For better or worse APS-C feels like the new standard for 2x3 sensors.