According to JIVE Records via MTV.com, the "Radar" track appearing on Circus is "the same song, but it might be a different mix."
I dunno why everyone is complaining about the song being on the CD. Everyone wanted it to be released as a single and have a video. We might get that now!
EDIT: Yes, I realize that Bonus tracks don't normally get that kind of attention, but recall that Jay-Z's first single off American Gangsta was "Blue Magic, " a Bonus track. They could also film a video and make it an Extra or a Special Feature of buying the CD. I'm just saying, if they're putting it on the CD, I'm assuming they want to do something w/ it.