I'm using the current version already.
However, it is only used in 1 place and is disabled by default.
I use it in the MyPage
feature to enable drag and drop in Firefox. See the documentation for MyPage here
The reason it is disabled by default is because I cannot distribute those dlls and also it can't be used with Mono for quite a while.
I only use it in MyPage because its convenient and I don't know another easy way to get drag and drop working in Firefox for WebParts.
I don't plan to use it anywhere else soon because I don't want additional barriers to running on Mono. Instead I use other things like MagicAjax, Prototype, Sarrissa, Dojo to implement AJAX in a cross platform way.
To use MS AJAX in mojoPortal, see the AJAX Extension Pak download.