Here's screensaver hack for K4 :
http://dl.dropbox.com/u/16679763/upd...0.26.N_k4w.zip
Of course jailbreak is required.
Installation :
- unpack archive
- copy update_ss_0.26.N_k4w_install.bin and data.tar.gz to your Kindle
- update from settings menu
- reboot from settings menu
Cheers