Even though it hasn't been all that long since the m.4 release, there has been a lot of things going on in the community. Firstly, m.4.0.1 includes a bunch of security updates, compile updates, protocol updates, etc. There are some features that you won't see in m.4.0.1, however, which includes tabbed chat dialog and improved script-enabled IRC. Those, I believe, are targetted towards m.4.1 release.
Other than the software itself, core developer Rainwater has left the team due to personal (time consuming) reasons. As we know, earlier Egodust has stepped back and taken a watcher role due to some of his personal (time consuming) reasons. Currently, we do still have all our protocol developers actively working with their designated protocols.
Ghazan has been awesome and has added optional MSN Messenger 7 protocol support. ICQ, Yahoo, Jabber, and IRC has some important updates too. m.4.0.1 release is coming close, however, there have been no date set yet. Those bold enough can test the nightly builds and report problems in the user forums.