Kellan outlines the bare minimum you should expect from any service that you are putting data into.
Paul Mison shares his thoughts on moving towards a decentralised web of services rather than silos of data. "Now I'm wondering: is there a space for a piece of user-installable software, like Movable Type or Wordpress, that aggregates their data from sites across the web, and then presents it as a site? If there is, is it even possible to write it in a way that anyone who couldn't have written it themselves can even use it?"
Steven Pemberton's talk from XTech 2008 in Dublin is becoming more relevant with each passing day as yet another service shuts down; Pownce, Ficlets, Stikkit...
All of Google's data APIs (Calendar, Blogger, Contacts, etc.) all now support OAuth. Excellent!