Foursquare has done a little overhauling of their home page today. In a post entitled "A little nip and tuck", Foursquare outlines some of the changes they've made to the site. The most noticeable difference is the cleaned up main page for logged-in users, with more of an emphasis on what your friends have been doing lately. It should make it easier to keep up on things from your desktop.
Also fixed up the tools for finding friends, making it simpler to add and manage them.
There're a few other random tweaks and clean-ups.