Earlier quoted context omitted.
Agreed, the valuation makes no sense to me. There's really no switching costs that I see. Bitbucket is actually superior in many ways because of its tight integration with Atlassian - the real Microsoft Word of the Developer community. Sourceforge had this kind of play at one point and look at it now. Maybe they're going to start displaying ads for jobs for developers. Not sure that's worth 2B though...
Yet to meet a developer who's as excited about using Jira as about using Github issues...
BitBucket+Mercurial is sweetness as a developer. Better than TFS, far better than Git, and well, everything on the planet is better than ClearCase.