From the changelog:
* V5.1.0-2006-12-30 (see also: Release Notes at http://knopper.net/knoppix/knoppix51-en.html)
- Update to Debian etch/testing as base distribution
- Linux Kernel 2.6.19(.1) + fuse 2.6.1
- cloop 2.05 Realtime Decompression with extended block-buffering for reduction of CD/DVD access latency
- Replacing unionfs by aufs for better stability & performance
- KDE 3.5.5 + [DVD only] GNOME 2.14
- OpenOffice 2.1 (german and english)
- Iceweasel (formerly known as Firefox) 2.0 and Icedove (f.k.a. Thunderbird) 1.5.0.9
- ntfs-3g (12.12.2006) for full transparent NTFS write support, also tested with boot options knoppix tohd= and knoppix romhd=.
- ntfsprogs-Update (ntfsresize, ntfsmount, ntfsfix)
- integration of 3D desktop beryl+emerald as add-on for KDE (manual start with gnome is also possible), via boot option knoppix desktop=beryl.
- Experimental script for creating a bootable flash-pendrive from a running KNOPPIX live session (mkbootdev by Martin Öhler)
- [CD] removed mysql because of space reasons.
- very new version of frozen-bubble with LANmode support