For a lot of us, that would be next Friday.

At some point - most likely after noon PST - version 0.9 of the API will be replaced with the final 1.0 release.

<strike>There are no expected interface changes between now and 1.0.</strike>  
There has been [one chang][1]e in the 0.9 timeframe.

This question will be updated once the transition has occurred.


  [1]: http://stackapps.com/questions/1048/in-the-timeline-the-ability-to-know-what-events-belong-to-what-question