CiviCRM Community Forums (archive)

You should be able to do this with Groups via profiles. The profile create form can include the list of available groups (i.e. teams) that a person can signup for. You can use a separate search page or list display to allow people to view current members of a group/team.

The workflow would look a little different from the example you provided, but the core functionality would be the same. Though I guess if you're looking at having hundreds of teams, it would be better to have the search functionality rather than just a listing. It would take some custom work to mimic that flow.

Have you checked out the Personal Campaign Page functionality that was added in 2.2. It's not "team oriented" - but it has pretty complete support for individual fundraising pages - and I guess the individual could be a team leader.

Also, the folks at RASantiago (https://www.rasantiago.com/) recently demo'd a CiviCRM site that is oriented around team fundraising. You might want to ping them to discuss their approach relative to your requirements. (CAVEAT - they use ModX CMS rather than Drupal or Joomla!).