Can different systems(let's say a ps3 and a 360) play each other online?

May be...

The reason why I'm asking is because I'm thinking about getting a PS3 and my buddy is getting a 360. We're worried that we wouldn't be able to play online together.

No. Unfortunately, these to systems can not connect to each other online. The reason for this is because Sony and Microsoft use two different servers.

i think you can if you both get to buy the same games but the 360 one has to say x box live on the top i heard all you have to do is get your friend creator name and then you can send a request to answer or he will to you i still think it might not work why dont each of you get a ps3

if you're thinking of buying a playstation 3 you should out this site first. they give you a ps3 for FREE! all you need to do is complete a few quick tasks for them.

Not yet but i think some platform crossing games are coming.But I think its from PS3 to PC and 360 to PC.

Sorry but no and that will never happen

no