I have been testing the different installs & find the following error message with Moodle 2 RC2 - today's build & yesterday's:
It is required that you store all your data in Unicode format (UTF-8). New installations must be performed into databases that have their default character set as Unicode. If you are upgrading, you should perform the UTF-8 migration process (see the Admin page).
There isn't a problem with RC1 - or the build from Sunday or 1.9 - I only get this with RC2.
Clearly all is in unicode format already. I did however turn on & made InnooDB the default engine a few days ago.
But then the other installs are not showing this message.