http://www.canonrumors.com/2013/10/sigm ... -os-outed/
Doesn't sound that exciting, but it's a popular lens range for FF users (and useful on APS-C too)
Bearing in mind Sony stopped making the 24-105mm KM re-badge, they don't actually have a 24mm zoom lens other than the 24-70mm F2.8 ZA SSM which is a wallet busting £1300+ right now. Actually they don't even have a a normal 24mm f2.8 prime either. Just a 28-75mm f2.8 re-badged Tamron as a more affordable FF offering zoom wise
Subject to good optical performance and reasonable price it could be a bit of a sleeper.
BTW another Canon user friend of mine had their 24-105mm L go tits up with the Error 01 problem (aperture won't open/close properly evidently a ribbon cable issue)
Could be one to watch we'll see.