This is simple.
First, get the package
Go to http://www.google.com/chrome/eula.html and select the 32-bit .deb for Debian/Ubuntu, then click "Accept and Install". This will download google-chrome-beta_current_i386.deb.
Optional: Prevent Chrome from adding the Google repository
If you want Chrome to keep itself up-to-date, don't do this step. However, if you just want to check Chrome out without changing too much, you might want to type the following command at the command line:
EDIT (8.5.2010) - No longer works. I give up, Google. The new interface is worse, but I suppose I'll get over it.
EDIT - This method no longer works. Google has updated their Labs search to use the new layout. Instead, you can use this URL to keep the old-fashioned Google:
I saw the new Google search results page layout for the first time tonight. I then googled "turn off new google layout". I suppose I don't handle change very well. If you hate the new Google layout too, here's how to fix it: