We've got tabindex attributes on form elements in a lot of forms to make tab order feel natural...
Unfortunately something seems awry in Firefox 3.0 beta (tested betas 3 and 4). Going to Special:Userlogin and hitting tab *should* bump you straight into the username field, but on FF 3 you have to go through all the links on the page first. :(
Not sure if this is some problem with our markup or if it's just a FF regression.
Version: unspecified
Severity: enhancement
URL: http://en.wikipedia.org/wiki/Special:Userlogin