In the non-programming world, 2.0 is a marketing word to mean "the next great thing since our first product, it will replace and revolutionize the market!"
In the programming world, 2.0 means "we threw out the original codebase and started working on another"
So bitshares 2.0 refers to the programming term, not the marketing term.
In versioning programming semantics, 0.x are all building towards the 1.0 release.
The first digit changes where there is a significant functional incompatibility with the previous release. Since BitShares 2.0 is not compatible with the 1.0 API (which the 0.x tree was developing), it needs to be indicated with a different version number. I'm guessing we'll see things like "2.0-beta1" "2.0-beta2" etc. in versions going forward to indicate the difference in API.http://en.wikipedia.org/wiki/Software_versioning
As for marketing, call it what you want - but for our internal community discussions, we need to be clear.