Will there be an OpenAds for Drupal 6.x?

yes there will! I will be opening a new development branch for Drupal 5 for new features shortly.
At that time I'll start looking into porting to Drupal 6.

I have added in support for the Remote and Local invocation methods
for OpenX (Openads) to go along with the XML-RPC method currently
in the development snapshot.

If the next snapshot release proves stable and working then that will
become the basis for the port to Drupal 6.

So if you can help to test out the latest drop of Drupal 5 openads you
will be helping to speed along the move to Drupal 6.

For anyone following this thread, what other features would you be
looking for in a Drupal 6 version of openads?

I just ported openads to Drupal 6 and you should see a development
snapshot appearing on the project page in the next 12 hours or so.

Please take a look and open any new issues with Version 6.x-1.x-dev if
you run into problems.