I'm currently developing an application using BeerXML v2.06, based on the <version /> stated within the Medieval Ale example. It very well could be v2.07 for all I know. I'm creating the app as a 'free time toy' and still month away from a beta release.
From what I gather, v2 will become standard once people start using it and the spec has stopped evolving like you already pointed out.
Hope this helps,