PS3 Achievements System Q

I'm looking at getting a PS3 in the near future. I'm looking around now and getting a feeling for the system and how everything works. I only have one question:

I know that the Xbox 360 has a built in achievements/awards system in their games and such. Gives players something to work towards when playing. I hear lots of good things about it, by and large. Anyways, I was just curious if there was such a system in PS3 games and, if so, how does it work. Does it add anything to your gaming?

Thanks folks!

So there are trophies that you store at home? Is this only going to work with games after a certain point or is this something that has been working for a while and just hasn't been implimented?

I never thought I would like this kinda crap, but playing Orange Box on PC and having things to work for is amazing. I wouldn't have done half the stuff I did in Portal if it wasn't for achievements. So I'm kinda hoping for a good achievement/trophie system on the next gen system I decide to get.