Problem
I upgraded to Suse 10.1 and enabled XGL and Compiz (http://en.opensuse.org/Using_Xgl_on_SUSE_Linux) which looks absolutely AMAZING. The only downside so far was that SQL Developer would not start. After a little research, I discovered this is not a SQL Developer issue, but a problem related to ANY Java Swing app on Compiz.
All you see is a blank screen with the "Assert: Unknown Node:8" lines on the shell. As Kris has stated before, the "Assert" lines can be ignored, but I'm trying to post as many keywords as possible for someone to find this who was running into the same bug.
Solution
While this is by no means pretty, it actually works really well. Essentially you startup the MetaCity window manager (.5 seconds), launch SQL Developer, then restart compiz (.05 seconds).
Here's the commands to execute from a shell:
metacity --replace &
sh sqldevloper
compiz --replace gconf &
I found the solution in this blog:
http://www.vijedi.net/wordpress/
If someone takes the time to script this, can you please post?