Install Ubuntu in Parallel to Mac OSX
If you are trying to do this you will need Parallels Desktop 3.0 for Mac (~$79.99 USD). This software allows you to run Windows and Linux on your Mac so you have access to all three operating systems without rebooting. I think this will be an ideal web developing environment, but that is another article all together...
Install Parallels Desktop 3.0 for Mac and then launch it. Go to File -> New. In the new window select Typical, then click (Next). Select Linux and Ubuntu Linux, then click (Next). Finish the guide with the appropriate information that you want for the system.
I got an error when I tried to install Ubuntu 7.10 (Gutsy):
The display server has been shut down about 6 times in the last 90 seconds. It is likely that something bad is going on. Waiting for 2 minutes before trying again on display :0.
If you get this error, follow this guide in the very good knowledge base provided by Parallels.
You can't Update Ubuntu
You have to manually connect to your internet connection. Just go up to the top right of your Ubuntu screen and select 'Wired Network' from the network monitor and it will connect (assuming your Mac has an internet connection). Also since the install could not find a connection, it may have commented out all of your repositories in /etc/apt/sources.list. Follow this guide to set up your repositories (you should probably use these repositories anyway).
Can't start Ubuntu after an Update
For some reason single gets added back into the string 'kernel /boot/....' in your /boot/grub/menu.lst file. Refer back to step 5 in this guide to fix that problem.
Note: My machine crashed after the update and before the reboot which may have caused this issue.
Cant use Full Screen Resolution
If you are getting warnings telling you that you cant set a resolution that size when you start the Ubuntu machine, check out this article. Basically, changing the setting in /etc/X11/xorg.conf does not work, you have to use sudo dpkg-reconfigure -phigh xserver-xorg to change the resolution settings.
At this point you should be set. Enjoy the wonderfulness of Linux on your Mac... :)