Maybe. :P Actually, I've got no idea exactly how much Rising will have to do with MGS4. First it was supposed to take place before MGS4, and now I guess it takes place after? Or maybe I have that backwards...
But yeah! I loved MGS4. It gets a lotta crap for basically being a huge movie with a few interactive moments in between cutscenes, but I still love it. Make sure you've got plenty of spare time to play it, if you want to watch all the cutscenes and all that stuff.