For a lot of us WPF is still a new technology. There are a few commercial applications out there, a few component suites... but it is still not common in the "typical windows app".

I was looking for blog entries by MSFT staff to find out when the first releases were published. And it looks like it was around 2003/2004. The interesting question would be: When did the development process for WPF start? I don't know when the whole process started but you can look for when the implementation of the real thing (not counting first test releases) started in BamlRecordReader.cs (available via .net 3.5 source code in VS 2008):

/*****************************************\
*
* File: BamlRecordReader.cs
*
* Purpose: Main class to handle reading a Baml file
*
* History:
* 6/06/01: [...] Created
* [...]
\*****************************************/

Baml is the binary representation of XAML. As there were two different "compiled" versions of XAML (CAML & BAML) available in the first bits of WPF we can assume that the Baml classes were one of the first classes (I don't know if CAML was used before BAML but as I don't have any reference source for CAML [CAML was discontinued after the first bits] I cannot event check the dates in there).

Looks like the WPF project was well underway in mid-2001 (to get a feeling: XP was release 10/25/2001).

Was the WPF project already started in the 90's? If yes, it would be more than interessting to see what's currently developed within MSFT...

Don't take the dates for sure. This is just guessing from the external world and could be all wrong.

 - tobias