Mageia 3 Alpha 1 ships with the Linux 3.5.3 kernel, glibc 2.16, KDE 4.9.0, GNOME 3.5.91, and various other package updates. One non-package change for Mageia 3 is the Unix /usr directory unification work that's also being done by many other Linux distributions.
The release notes for Mageia 3 Alpha 1 are available from the Mageia.org Wiki, but there isn't much to them. While there isn't much to this first alpha, a list of accepted/proposed features for Mageia 3 are available from the feature review page.
Live images of Mageia 3 Alpha 1 are not available since the UnionFS used by the live environment is currently having issues with the Linux 3.5 kernel shipping in Mageia 3. With UnionFS being unmaintained upstream, for Mageia 3 they may end up maintaining it themselves or switch to another file-system like OverlayFS or AuFS.
The current Mageia 3 road-map has the final release scheduled for 20 March 2013 while coming in October and November will be two more alpha releases, a beta release in mid-December, two more betas in January and February, and a release candidate in early March.
This first Mageia 3 alpha release can be fetched from the Mageia Mirrors.