Actually this is one of the features I love about the PS3. I have two PS3's and I have the same PSN ID's on both. Any achievements you gain on one, is updated on the other (As long as both consoles connect to the net. You can't do it by networking them together).
The only thing you will need to do is copy your save games to a USB stick to transfer your save games.
Now for the added bonus ... As long as you have the same PSN ID you purchase your market place files with on both consoles ... you can down load the files on your second console with no extra charge!
For example: I bought Monsters on my first console. When I got my second console, I added my PSN ID to the new console and downloaded Monsters again at no charge. (All "owned" files from the market place are marked with a red symbol.)
I wish I could do this with my XBOX's. You can't even have your gamer tag on two consoles
The only way I can do it is have my gamer tag on a MU and transfer that between consoles.