As you maybe already noticed in the article at wodpress.org from Aaron Brazell, the plugin developers are encouraged to update their plugings. So I start and install WordPress 2.1a3 and trapped direct into the biggest upcomming problem for plugin developers: The visual editor (TinyMCE) is updated and didn’t support anymore a Button integration in the old way (with buttonsnap.php).
I said to myself : Ok, no problem let’s have a look in the WP Codex pages for the new function description, but for my own suprise : There is simply no documentation or link on 
After I google through the web I found only two plugins which are at the moment able to handle a button integration (Anarchy Media Player and Viper’s Video Quicktag). I need now to do it by hand in the same way , but I’m real unhappy about this fact.
Hope the WordPress developers remind this gap until they release WP 2.1…
Otherwise I must ask :
Is WordPress 2.1 Naughty or Nice?
UPDATE 20.01.2007 :
Today I finished a short description, for a work around the button problem. See this post
I must say : Horrible and again horrible…
After 6(!) hours I got working the new wordTube button under WordPress 2.1 TinyMCE editor. It’s now ok, but not what I like to publish. I will start maybe later to rebuild buttonsnap.php for WordPress 2.1 , but I feel my programming knowledge are really not enough for that…
Did you report this as an issue on Trac?
No not now, I’m not a skilled programmer, so I only ask some people in the wordpress support for help. As you can see I find a solution by study two plugins…
The codex documentation must be updated before 2.1 get released,
otherwise other plugins get problems
I opened yesterday a bug at WordPress and it seems to be a issue for WordPress 2.2. Hope we find a solution.
See the upcoming changes here http://trac.wordpress.org/ticket/3551
Update : Seems to fixed maybe earlier :
See here http://trac.wordpress.org/ticket/3563