rEFIt hasn't been updated since early 2010. My fork of it, rEFInd, is under active development and includes features to help with booting Linux, so it's a better choice than rEFIt in most cases.

Unless you're triple-booting with Windows or some other BIOS-only OS, I recommend at least trying to get a native EFI-mode boot of Linux working. This means you should not use Boot Camp or create a hybrid MBR -- in fact, much of my reason for offering this advice is because hybrid MBRs are so dangerous, as the linked-to page describes. That said, some users with some models report that some hardware (typically the video hardware) works poorly or not at all when booted in EFI mode, so a BIOS-mode boot of Linux may be necessary. I recommend you consider this a fallback position, though.

I've written a Web page on installing Ubuntu on a Mac in EFI mode; see here. Unfortunately, that page is a bit outdated, and my only Mac is a rather old 32-bit model, so some details are likely to be different for users of newer 64-bit Macs. Still, it may be a useful reference.