I am surprised that it is already almost a year since OMDoc 1.2 appeared, and we have to do something.
We have been thinking about the future of OMDoc Version numberings. Currently OMDoc is at 1.2, and we have collected a lot of ideas for 2.0. Some of them have been presented at the MKM 2007 Workshops, and have met friendly comments. Somehow a direct push towards 2.0 seems scary, and it may be better to use the summer to make a revision 1.3 with these new ideas, bring it out, and move on to the next set of ideas and improvements.
We came up with a new scheme: we will try to have our cake and eat it: we come out with a specification that is somewhat incremental soon (I guess fall) integrating the new ideas, and call it 1.8. That shows that we are on our way to 2.0. This version will be incremental in that we will mostly only add things, and redefine the old syntax in terms of the new, and deprecate some of the old syntax (e.g. the use of xslt in the presentation elements like we do in content MathML3). Then we have one more version (1.9) to accumulate new stuff (e.g. the new MathML3/OM3 syntax), and in 2.0 we will throw out the accumulated deprecated functionality.
That will give us a relatively clean roadmap towards 2.0, I think.