Our API directory now includes 50 backend APIs. The newest is the CloudBees API. The most popular, in terms of mashups, is the CloudMine API. We list two CloudMine mashups. Below you'll find some more stats from the directory, including the entire list of backend APIs.
Three months after its initial launch, much-talked-about data portability service Gnip has released version 2.0 of its API, as well as the first glimpse of a business model. As we covered back in March, Gnip's goal is to "connect Data Consumers to Data Publishers in a low-latency, highly-scalable standards-based way." Gnip is a sort of proxy that makes data from diverse Publishers--services like Delicious or Twitter, which create activity content--available in a unified format, and notifies Consumers--like FriendFeed or Plaxo--via a push interface when new data is available. The new version of the API adds full data delivery, XMPP support, and advanced data filtering.