So I was browsing the new Camera Raw that comes with CS5 and man did I find a great new feature. In CS4 you were able to change only a few options in ACR when it came to lens distortions. Well in CS5 i went to the tab "Lens Corrections" and the new feature is the first screen "Profile." Here you click on "Enable Lens Profile Correction" and it takes the information from your Metadata and picks the correct lens and fixes the distortion!!! This is an insane feature that is highly useful. In the vide I just took you can see that without the correction the building looks quite 'bubbly' and with correction it looks more correct. Give it a try, it's neat, although it doesn't work every time.
http://vimeo.com/15837221
http://vimeo.com/15837221