It's worth mentioning that the bid logo is generally different from the logo of the actual games. London's bid logo was a much more attractive (if less attention-grabbing): http://en.wikipedia.org/wiki/File:London_2012_Olympic_Games_...

I'm not sure why they change the logos, given that the final logo is almost always less attractive than the bid logo. In Sydney, frinstance, we had a nice neat bid logo (http://en.wikipedia.org/wiki/File:Sydney2000bid.png) which for the actual games they decided to unnecessarily complicate with a running man and some boomerangs: http://en.wikipedia.org/wiki/File:Sydney_2000_Logo.svg

Nothing nearly as bad as London 2012, though.