You can now subscribe to a search in Google Base so that you can watch for new items people might add. After performing a search in Google Base you just have to select the RSS icon located in the upper-right corner of the screen. You then continue appropriately depending on how you normally subscribe to new feeds.
If you have a full feed reader (not something like Firefox’s Live Bookmarks) then the entry in the feeds should appear similar to the image below. I was actually surprised to see that Google included pictures of the items so that people don’t even have to go check Google Base to see what the item looks like. Google also has a page designated to the RSS specifications in the help section.