Stefan Löffler has posted to the TeXworks mailing list the following:
Windows binaries and a source code bundle have been uploaded to GC, and Ubuntu packages are currently building (see https://launchpad.net/~texworks/+archive/stable/+packages). The web page (http://www.tug.org/texworks/) will be updated soon (just waiting for a routine pull from the GC repository). For a quick overview over the most important changes, please have a look at http://code.google.com/p/texworks/source/browse/tags/release-0.4.0/NEWS
This is very much evolution in TeXworks development: I’ve been using the unstable builds for some time with no serious issues, and doubt that will change much with the release of v0.4.0. I’ve quickly tested the Windows builds, and have also done a quick build on Ubuntu (see the screenshots). You will see that Mac OS X builds are currently missing: getting them working is currently proving to be something of a difficult task. So for the moment, on the Mac you have to stay with older (but quite usable) builds.