I used javascript for years to mask the ugly click-tracking URLs, showing the user a clean http://www.somewhere.com domain in the status bar instead. However, a few months back, I stripped out all that onmouseover and onmouseout code.
The reason?
Firefox users don’t see it anyway, and more importantly, neither will IE7 users. The default in IE7 is to disable script access to the status bar. I’m sure there were plenty of devious sites abusing this concept, so we have them to blame for its demise.
I think cloaking links in this way is pointless these days, and will become more and more so.