Tamron 24-70 VC= 1000€
Canon 24-70 I = 1200€
Canon 24-70 II = 2300€
from what I gather (i do not own any of these lenses, much to the pitty), the Tamron is egual to, if not better than the Canon mkI in optical quality and is ~20% cheaper AND has VC. The Mk II is hailed to have supirior optics, but no IS and costs 2.3x the price... An IS version of MkI or MkII would be closer to 3000€ (as dilbert suggested), 3x the price of the Tamron... Seems a little overpriced!
I honestly think Canon is not in the most competative position for its standard 24-70 zooms... they are pricing themselves out of the race...
Competition is always good, any new lens from any maker is good for all of us, directly or indirectly! I say, let canon bring an IS version out, let it be stupidly overpriced, and let them learn their lesson!