Is Google App Engine a Facebook Competitor?

Yesterday, most of the buzz floating around was about Google’s new App Engine. The service has been hailed as the competitor to S3 but both Nate Westheimer and David Recordon say that the true competitor is Facebook. Nate says that the real problem with the new App Engine in comparison to S3 & EC2 is all the contraints. Right now all apps must be written in python and should integrate with the Google infrastructure. Trying to combine statements of Nate & David is somewhat complex since they have presented their arguments in different manners.