The latest issue of Game Informer has a heavy amount of details regarding Resistance 2. Considering the game hasn't been formally announced yet, it seems to have been in development for quite some time and is aiming for an Autumn release (so expect to see it in early 2009). There are some story details in there, but we're not the type to spoil. If you really want to know, pick up the latest issue of Game Informer.
As for game features, this looks to be the biggest online game yet seen on a console. There are two separate story modes, one intended for single player and one that will support two-player co-op offline or eight player co-op online. On top of this the online competitive mode will support sixty players per server. Warhawk, eat your heart out. There will be new vehicles, semi-randomly generated levels and a class system for online play.
Wait, did we say two story modes? One co-op and one single player? Does that not sound awesome? Yes, it does - because, from what we can see, Resistance 2 will be made of Awesome.
[UPDATE] The game is aiming for an Autumn 2008 release. Any expectations regarding an early 2009 release are solely down to the cynicism of the article's author.