I think I was part of the other discussion you're referring to. This is something I've noticed as well, but have found that rebooting isn't necessary to get the sound back. I just go to Settings->Sound->Phone ringtone, and just select a random ringtone to hear it play. This "wakes up" the sound.
I've reported this to Google as a bug. The more people who do it, the more likely they'll pay attention to it, so go here
Issues - android - Android - An Open Handset Alliance Project - Google Project Hosting
and either start a new thread or search for a similar thread to add to it.