Google App Engine to challenge Amazon, Ning etc.
Write your applications in Python ... w00t!
Update : OK, this is big, at least this is going "mainstream". Poor Ning, they had all the great ideas, Amazon too ... but it sounds like Google are taking the whole package : integrated development environment, database, python, logging, version control, multiple developers working on same code-base etc. etc. and bringing it to the masses.
But only a limited number of free accounts ...
Update 2: early chatter is complaining about Python-only, actually I'm not sure it's gonna be Python that people struggle to get their heads around ... I think it's gonna be BigTable.