Small note, this doesn't seem to be simply an unsolicited power grab on Arianna Huffington's part. From the Press Release announcing the AOL Acquisition of Huffpo:

Arianna Huffington To Lead Newly Formed The Huffington Post Media Group Which Will Integrate All Huffington Post and AOL Content, Including News, Tech, Women, Local, Multicultural, Entertainment, Video, Community, and More

It seems like her role as Editor In Chief of all AOL content was part of the deal she made, since this occurred after the Techcruch deal was done Arrington likely had little recourse at that point. (Huffpo was acquired after TC, any promises made to TC about editorial independence was prior to the new editorial leadership). "Promises" made when big companies buy little ones are always pretty worthless once the rubber really hits the road.