While no changes have been published to Challonge recently, I wanted to mention a few things that are being developed behind the scenes.
Scalable Brackets will soon be finished. This means you'll be able to zoom in and out when viewing brackets (very snazzy, almost done with this one).
Skinnable Bracket Modules - Colors, fonts, default zoom level, etc. will be configurable soon, so I'll be introducing embeddable bracket modules that can be posted on external websites and fit any design style. I'll probably have to charge a modest amount in blocks of 10,000 requests or so (server load will rise), but these should be pretty sweet and useful.
Improved Participant Management - Just a vision right now, but this one's pretty high priority for me. I want to spruce up the tool for adding/removal people, changing seeds, setting teams, etc. Plenty I could ramble on about this, but I'll spare you.
There are several other items on the horizon as well. If you emailed me a feature request, I haven't forgotten about you!