Thanks to the how to geek for this one..;)
Telling what version of Ubuntu you are running is extremely easy. You would commonly use this command to figure out if you are running Edgy after you upgraded from Dapper.
Ubuntu edgy (development branch)
Note that the version numbers might change over time. I’m running the beta version so that’s what shows up when I run that command. Either way, it should be clear that you are running Edgy.