Knoppix may be run with several desktops, and GNOME and KDE can be chosen with the desktop cheatcode. After the introduction of LXDE, there does, however not seem to be so much interest in other lightweight alternatives.
What about using Enlightenment and the EFL (Enlightenment Foundation Libraries)? This is used in a Ubuntu derivative called Bodhi Linux, and some users seem to be very content - it's seemingly not the best for newbies, though.
What makes Enlightenment particularly interesting to me, is that it is the preferred desktop alternative for the Tizen project for full-version Linux on mobile devices (as opposed to the kernel+Android stack approach) This is Debian-based, and shouldn't really be that far from Knoppix, porting Knoppix to mobile devices should become easier with every day now.
Using Enlightenment with Knoppix could provide one of the stepping stones to mobile Knoppix, or is this approach futile?
Without having asked about this, I guess KK's first answer will be negative. Knoppix is extremely hardware agnostic, but achieves that by sticking to hardware based on x86 architectures, and keeps the 32-bits approach. Not even a 64-bits version is in sight (if things haven't changed lately), and I have come to support his approach, IMHO it's very practical to chroot into a 64-bits system from hybrid Knoppix and doing everything purely 64 bits there.
This 32/64-bits situation will relatively soon be parallelled in the mobile scene, making the whole situation even more convoluted.
It will be very interesting to see how the Tizen project develops - but there will actually be several Debian-based mobile alternatives. A Ubuntu version was recently announced, and you can already download an alpha release of Bodhi for the Asus Nexus 7 tablet. The Knoppix take on this might be to adapt a minirt.gz for mobile devices, which I guess will have to be tweaked separately for each new device in the first place.
With 2-4GB of RAM and 16-32GB of internal storage on the upcoming devices, there should be room for a Knoppix compressed image+persistent store without wiping out anything else, setting up for multi-boot.
Vintage 5362 IBM System/36 Mini-Computer Mainframe 5291 2, CRT Terminal DM12N501
$249.99
IBM Type 4869 External 5 1/4in Floppy Disk Drive Mainframe Collection - UNTESTED
$65.00
6 Vintage Computer Tape Reels mainframe 3200 5000 data ibm magnetic processor
$99.00
IBM Type 4869 External 5 1/4in Floppy Disk Drive Mainframe Collection
$145.99
VINTAGE IBM Type 4869 External 5 1/4" ~ Floppy Disk Drive Mainframe ~
$159.99
Digital DEC LK201AA Terminal Keyboard RJ11 Connection Mainframe in original Box
$94.95
2 - VINTAGE MAINFRAME Fortran Format Punch Cards - IBM 80 columns
$3.49
Cray Research Supercomputer Cray X-MP ECL Logic Board
$149.99
Commodore Amiga 500 Computer w/Mouse and Amiga A520 RF Modulator As Is Untested
$299.99
Xargon 1 Beyond Reality RARE Game Floppy 3.5” Floppy Mainframe Collection
$349.99