CommunityWalk.com - This great DIY Google Maps site has undergone a major re-design that makes it even easier to create your own Google Maps. Additional premium services includes a way for you to include a full-featured Map on your own website (including customized color parameters and map blending).
Maplandia.com - Users can now create an account and add placemarks to the map (with links to Google Earth).
Associated Press News Mashup - Has added new categories: National News, Sports, Business, Technology, Strange
DC Boundary Stones - has added 6 more stones! Flickr photoset here.
Have an update for a mashup you've created? Tell others about it in the comments section!