Working from Capcom's sales projections, they could be releasing RE5 sometime between March and February of 2007.

The press release lists all Capcom titles currently "under development". It has three games listed as coming out for the PS3: Resident Evil 5, Devil May Cry 4 and Monster Hunter 3. These are the only PS3 games Capcom have announced so far. In the same press release, under "sales projections" for this fiscal year (ending March 7th 2007) they list 3 un-named PS3 games, presumably the 3 game titles they listed just above it. Assuming they expect sales of these titles to split equally, then they only expect the PS3 version of RE5 to sell 50,000 units this fiscal year, meaning it could not be coming out sooner than February.

The Biohazard Wii game is also listed as under development but unlike all the other games, no sales projections for it are given for this fiscal year, implying that it will ship later.

Source REhorror