I've tried it, it does work. Just make sure you get a compatible card. The Apple software raid is honestly pretty good though, and being free... well, that's not bad either.
http://www.hptmac.com/US/index.htm I have a RocketRAID 2302 that worked just fine. In fact, the drivers are included with Snow Leopard.
When comparing a good controller with software raid vs a raid controller, I saw no significant difference in performance. These highpoint cards are much better than the crappy Intel ICH series, and more stable, and faster than the jmicron crap. Having the ability to monitor your RAID from within OSX is a very useful capability. I would highly recommend considering OS X software raid with a good controller instead of a true hardware raid card. Now, if you're planning a 6+ disk array, maybe hardware raid would be worth offloading, but if you have a quad core system running at 2.6+Ghz/core, do you really think your system is going to struggle to handle I/O? It won't.
I hear good things about the LSI1068e also, but I don't have one to try out.