Ubuntu wants us to use
apport for reporting bugs. You will be asked a bunch of questions to provide information (so that takes part of the information you need to collect to file a bug report).
This is the official bug reporting method (page has not yet been updated to include links for Natty) with step by step how to in getting you to filing it.
There is just 1 small piece about kernel bugs:
For sound, X drivers, and kernel bugs: please open a new bug instead of commenting
on a similar bug: chances are that your hardware does not match the existing bug's
hardware, so the bug will not be addressed.
Good luck and please leave a comment if the answer left any questions :)