Hi John,
In general the initial NT5 build will focus on an update to all the javascript controls - ie upgrading prototype, and rico etc where necessary. I'll probably take the opportunity to add a few more scripts in as well that I've had my eye on for a while.
The multi-site support is also a big deal, and will make deployment of multiple systems easier.
Other than that there's no particular order. Typically I add the stuff as it's important to us - but I've _very_ interested in what others want as well.
Cheers
Bruce