If we told you that Android was the number one mobile OS worldwide, you shouldn't really be surprised by this point. By most metrics, the little green guy has overtaken the competition in just about every area, including sales, actual userbase, and ad impressions, as demonstrated here by Millenial Media's report. There are a couple surprises in the report, though.
For starters, while the iPad being the top ranked tablet is no surprise, the Galaxy Tab beating out the Kindle Fire is. The model in the report appears to be the original Galaxy Tab. The seven inch slate running Gingerbread.