According to Gamespot, GTA 5 is likely to be released in 2012. Gamespot claims that this information comes from ‘source close to the developer’, so take this with a grain of salt. Especially since Rockstar hasn’t revealed anything officially about the fifth part of this legendary series.
Moreover, and according to the same source, the game will be vast, will feature mini-games and its scale is vast.
We don’t know the platforms of release yet, but we can guess that it will definitely come on X360 and PS3. It will be interesting to see if a PC version of the game will be released alongside the console versions. Or will it be delayed again?