Been dying to try the new AJAXed-out Yahoo! Mail Beta? Well it turns out it only takes a few simple steps to switch your Yahoo! Mail account over to the new hotness. There's instructions over at the curiously-named Google Operating System, but they're a little vague, so here's the step-by-step:

1. Log into Yahoo! Mail and click on "My Account" and enter your password if prompted.
2. On the Account Info page next to the "Member Information" header click on "Edit."
   
3. Under "General Preferences" click on the link next to "Language & Content" or "Preferred Content" (mine says "Yahoo! U.S.").
   
4. On the subsequent page in the "New Setting" box choose Yahoo! United Kingdom, Germany, or France.
5. Click "Finished" and then "Finished" again on the next page.
6. You'll be prompted to sign a new TOS and then you should get an offer to join the Yahoo! Mail Beta.
   

Once you've joined, the setting will stick, so you can go back to "My Account" and switch your Language & Content setting back to whatever it was before. If you decide you don't like it, click on the "Switch Back" link at the top. As usual, your results may vary and there's no telling if and when Yahoo! will pull the plug on this particular trick.