I dont play those games that require the best crap out there such as a desktop with like 6G memory whatever. My 4G laptop does fine on most games, so I'ma say laptops better for more casual games and such.
Mine has way more memory than most laptops and it performs even better than most upgraded laptops. As far as mobility goes a laptop is a lot better if it has quite a bit of memory and wireless internet, but I still prefer my desktop.
Desktop all the way. It will allways have better perfomance than laptops. Yes, laptops are "evolving" but I still believe desktop is the way for gamers and programmers.
Also, it's way easier to upgrade your desktop with new parts. So if you want to, you can, with ease, keep your desktop up to date all the time.
I like having a handy laptop though, it's nice when going on vacations where I need my e-mail and such.