You might have come across the 'no sound' problem after a fresh installation of Ubuntu 8.10 Intrepid. Well, there are a couple of solutions around and this one worked for me :
1. Go to System -> Administration -> Users and Groups
2. Click on 'Unlock' and enter password.
3. Next, go to 'Manage Groups'.
4. Search for the groups 'pulse' and 'pulse access'
5. For both of these, double click on them and add yourself to this group by checking on the check-box.
6. Hopefully, you are done !! Logout with ctrl+alt+backspace, and login again.