Gowalla said a writeable API was coming soon. Today, the check-in API is available to developers. Though it took longer than anyone expected, the announcement and the API have some nice aspects to help developers use the new features.
Each week we see dozens of mashups added to our mashup directory and often these use and combine APIs that go beyond the typical Google Maps mashup of old. This past week three of the more innovative ones go beyond just maps by using APIs from Netflix, MyBlogLog and Flickr. Here's a quick overview: