I want to install Ubuntu 11 in its latest state (Beta 2)....but I don't want to reinstall everything when the Final comes out.
Can I update it from Beta 2 without reinstalling everything from a disc?
Yes you can update from the Beta.
According to the release schedule, there is no longer an RC and the final will be the next release, 28th April.
To update to the latest release version when it releases you can press Alt + F2 and enter
This will open the update manager with the ability to look for any distribution upgrades.
As a note. It's not wise to update to the latest version from a Beta and to avoid any problems will be better to install the final release as a fresh install.
keep updating your machine and you will be upgraded to release candidate
(but this will work only after the RC is released )