Something
Emporium

Here's a quick warning: installing Ubuntu 11.10 on a new Macbook Pro 8,2 was an absolute nightmare. I've been using Linux for about seven years now.

• MacOS is pretty particular, and I couldn't get it to boot from any USB disk, regardless of how I flashed it. unetbootin produces disks that don't work on Macs, so you'd better have some optical media around.
• 11.10 doesn't recognise the superdrive after booting from a CD into the installer. Combined with the first issue, this is pretty bad. It fails at the Debian Installer stage. There's a fix in ubuntu-updates, but not on the ISOs. Only the netinstall (not even alternate in expert install mode) seems to let you download updated packages before loading the rest of the installer from the CD (which is fatal).
• The default Ubuntu installs will assume you have a BIOS. You don't &endash Macs use EFI (a predecessor to the UEFI stuff you've been hearing about). From what I can tell, it'll gently caress the "hybrid MBR" in such a way as to make gptsync refuse to touch the disk ("Analysis Inconclusive, will not touch this disk"). Basically, your chances of getting a working boot are nil. I couldn't convince rEFIt to boot any install I did (and I did a few, including attempting to follow these instructions that don't seem to work on 2011 models &endash; they're a good read for clues anyway; Rod deserves a bit of coin).
• Supposedly, the ISO images marked *+mac.iso are better at this partition table and bootloader stuff. But I've read things that say grub-install still won't install the EFI payload for you. And anyway, ubuntu-11.10-netinstall-amd64+mac.iso does not exist, so you'll be screwed by the first problem anyway.

Supposedly, the way to go is for a full EFI boot. This is getting easier with new versions of the kernel (you want at least 3.0 to avoid major headaches with hardware support). There's also the grub-efi-amd64 package. If it did what it should, it would install some sort of EFI payload (grub.efi?) that either MacOS (hold down alt/option) or rEFIt could boot. But there's no indication where this payload is, and I assume you'd have to manually move it to the HFS+ or EFI boot partition so that rEFIt/MacOS can read it. (Hell, all the older instructions say you'll be compiling it yourself.)

For now, I'm booting off an optical super grub2 disk and chainloading into my actual grub2.