Direct From The Source
For those who don't know, an API is a structured interface that other software, like PHP websites and such can connect to, to query for data. Think of it like providing data to create a stats page, much like you see for Common FPS games (eg bf3s.com).
From the looks of it all, It should be quite interesting.
There seems to be a few levels to it.
Career Profile: This is like your main account, it will list your Heros you have associated with the account and the Basics of each of them, their levels and progress through the ACTs.
then;
Hero Profile API: This looks at your Hero in more detail, when your toon was created, last played, active skills, Elites kills, how much gold you've collected, blah blah. All the Atributes you can shake a stick at (dps right? - yes)
I forsee the vBulletin community developing a package/api purdy quickly when they release the final API code to the public - no release date annouced yet, but from forum and twitter posts, they seem to indicate that it's soon.
What does soon mean though, in Blizzard terms? - yeah, could be tomorrow or next year.
So exciting times ahead for Diablo III Junkies, coz we may have a new Toy on this site.
*NB
Please make sure that if you find a Gesture of Orpheus or Beckon Sail, that you make sure they get to me PRONTO.