The Vanilla Forums PHP SDK by Vanilla Forums integrates discussion modes into online communities. Individual add-ons include language as plugins, templates as themes, and scripts as open source tools. Additional information to customize and integrate forums with cloud solutions available at https://github.com/vanilla/vanilla
Our API directory now includes 78 hosting APIs. The newest is the MongoHQ API. The most popular, in terms of mashups, is the Heroku API. We list 13 Heroku mashups. Below you'll find some more stats from the directory, including the entire list of hosting APIs.
Earlier today Google announced the release of Sidewiki, a universal web page commenting system that allows anyone with the Google Toolbar to add comments and feedback on any web page. The web is abuzz with the news. The video included below gives a good overview of how Sidewiki works.