Meh, I'll pick up the PS3 version on release and then for the PC when it gets cheap, mainly for the mods. Going by past history I expect the PC version to be announced shortly after the New Year for a late Spring release and a next generation version announced in the Summer to come out in the Fall just in time for the holidays in a "GOTY" type package. Plenty of people will double dip for that even if they already bought the current gen version the year before.
I'm sure there will be a lot of improvements on the PS3 side compared to how GTA IV and RDR performed given how many years its been. Probably still won't completely match the XB360 version but it should be closer at this point.