If you're curious to see what's happening to make the upcoming release possible you can see our progress in the meeting notes of our weekly (public!) core dev meetings:
Also, if you want to see all the features/changes that were submitted for possible acceptance into jQuery 1.6 you can see them in our massive spreadsheet:
To overview our process: We collected feature/change proposals from the community at large for a few weeks in a Google Doc form. The jQuery core team and jQuery bug triage team (and some members of the jQuery UI team) each added their personal opinion on the features to the spreadsheet (linked above). We used that to form a rough consensus, ironed out the final details in a meeting (see the notes from the March 14th meeting). We're now pushing ahead on those nominated features and you can track our progress in the weekly status updates or, if you want to live on the edge, in #jquery-dev on irc.freenode.net.
It's actually a great time to get involved in contributing to the project - I highly recommend it!
Keep up the great work!