DSEmu 0.4.10 is now available:
http://www.double.co.nz/nintendo_ds/dsemu.html
This has a few new DS graphics features implemented incuding sprites and 8 bit modes. The sprite support has resulted in a few more demos running that are actually playable.
I've posted about the various fixes at my weblog:
http://www.dsdeveloper.co.nz/2006/01/dsemu-0410-is-out.html
Unfortunately the annoying thumb emulation bug is still there but I've put a workaround in place. Hopefully I'll be able to fix that in the near future as its the major reason why some demo's crash or black screen.