On both Feisty and Gutsy, there was no sound on installation. The problem is that the DCA channel in ALSAMIXER was set to zero. The first time I saw this problem in Feisty, it took me a week to figure it out. Most recently I saw it again in a clean Gutsy install, and it took me 8-9 hours to figure it out, because of course I forgot about my previous experience. This may be "working as designed", but it is incredibly frustrating and I decided to file a bug report so others can reference the fix (including myself when this happens to me again.)
A great first step in troubleshooting lack of sound is to open a terminal window and type "alsamixer". The ALSA tools might not know your default card, and result in the following error, "alsamixer: function snd_ctl_open failed for default: No such device", but before you go and try all the troubleshooting guides that recommend reloading modules, try, "alsamixer -c 0" or "alsamixer -c 1".
You should be at a text-GUI (aka: curses) for alsamixer. Scroll through each channel and set them all to 100% with the left, right, and up arrows. Also unmute all channels with the space-bar key. You may need to hit the tab key to get to other interfaces. Check the top-left of the screen to make sure the card you are configuring is the one you expect.
Now that all your channels are maxed, open the GNOME sound configuration tool. (System -> Preferences -> Sound.) You do not need to close the alsamixer or save the settings for them to take effect. Play with the Sound Playback drop down choices and click the Test button. Some may give you errors, and that's okay. Hopefully you will find a setting that works.
Lastly, return to your alsamixer window, which should still be open. While the tone is playing from the sound configuration tool, lower the active channels half way or so, and lower the inactive channels even more. At this time you may want to mute some channels (again with the space bar) or set channels to zero. Do this while the sound is playing so that you know you are not muting your primary sound again.
The Linux sound system can be confusing. There are GNOME sound levels and ALSA sound levels. You have to be sure neither are muted in order to get sound output. It doesn't help that some of the channels are called things like "DAC" (which means Digital Analog Converter, by the way). The problem - the bug - here is that Ubuntu installs with some of these required channels set to zero or set to mute, and dozens of people ask for help on this issue every day. Hope this information finds its way to some of them.
A quick correction: That should be the M key, not the space key, to mute and unmute sound channels.