Newer laptops are becomming more and more upgradable. A while back, they didn't even use socket processors like desktop, but rather a little board. Some current laptops actually have sockets. My laptop actually has a socket 754. Now, I've never tried upgrade mine, so I'm not sure if it's limted to "laptop" processor, or if you could use some other processor.
I know my processor is located under the same flap that you remove to access the RAM. Most probably aren't, but I'd look around to see if I could expose where it probably is. Once there, it's pretty obvious if it's a similar socket to a desktop, or something totally different.
Another drawback to laptops is what processors they can use. Normally the bios support is rather limited. Technically, my laptop could run a Turon 64. However, this is only acheived with unofficial bios flashes and stuff like that...