is it worth it to save up for a ps3 for games like uncharted 2, mgs 4, little big planet, killzone 2, god of war 3, and resistance 2 if i already have a 360?

Yes.

Why are all these Should I buy a Ps3 topics coming up the day Uncharted 2 is being released, but to be fair, Uncharted 2 looks AMAZING from what I have seen. Actually wants to make me get one.

A month ago no, today, yes.

if you have the money to own two machines, then sure

From the looks of your list, it seems like getting a PS3 would be worth it for you.  My rule of thumb has been to buy a system when the exclusive games you want for it cost as much or more than the system itself.  I would recommend though that you skip Resistance 2 and consider getting the Rachet and Clank Future series.

yes

Don't forget Valkyria Chronicles. For me, it won't be worth it until they include backwards compatability, but you seem to have more must have games on your list than I do. For me its just MGS4, Valkyria Chronicles, and Heavy Rain

 Yes. 

Nope.

" Nope. "

I think it's a pretty good time to buy a PS3.

I would say so. Next year is going to be amazing too.

I would say that MGS4 was highly overrated but yes, based on that list (I would probably add Infamous and Demon's Souls to that list as well) it is more or less worth it.