Rob, Paulo, Herbert,
It is important for the BIBFRAME Early Experimenters to gain consensus on specific use cases and requirements before any collaboration could be useful. Casting the initial BIBFRAME requirements to "accommodate and distinguish expert-, automated-, and self-generated metadata, including annotations (reviews, comments) and usage data."  as Web Annotations isn't something that was initially well understood, but from my perspective, the progress around this mental shift has been quite impressive. The BIBFRAME EE group has agreed to share work early and often for supporting such collaboration. In that light I'd consider the draft BIBFRAME annotation doc a start of such a process you've suggested, not the end.
The general architecture that OA has defined includes a large set of use cases that are not the same as the more resource-centric ones that the EE community is focused on at the moment. Further, BIBFRAME concept / carrier distinuctions are important to its underlying model, so tying annotations to any Type list that doesn't align to this will be problematic. As such, an initial take on a smaller solution space (rather than the general one you're addressing) is bound to differ. Talking with Ray Denenberg (the Editor for this doc) he sees the compatibility and interoperability differences to be minor to negligible, so it may be that we're not so far off on the compatibility after all. My understanding is you'll be meeting with folks form LC this week and I look forward to hearing how these discussions go.
The requirements are different. But as you've mentioned, there is overlap between the target communities and working together on supporting the needs of this overlap certainly makes sense.
President, Zepheira "The Art of Data"
 A Bibliographic Framework for the Digital Age (October 31, 2011) http://www.loc.gov/marc/transition/
On May 3, 2013, at 4:14 PM, Robert Sanderson <[log in to unmask]> wrote:
> Dear Sally, Ray and all,
> As co-chairs and co-editors of the W3C Open Annotation Community Group, Paolo, Herbert and I would again like to invite members of the BIBFRAME group to continue the discussion of interoperable annotation on the mailing list for the W3C Community Group. There is neither a cost nor membership requirement to joining.
> We feel it is fair to say that the Open Annotation effort has gained significant momentum, being the 6th largest community group with many active and ongoing discussions. However there is always room for improvement, and we still believe that both BIBFRAME and Open Annotation would benefit from an open discussion of the issues that resulted in the divergence which is clear in the annotation document.
> It is regrettable that the BIBFRAME annotation model is neither compatible nor interoperable with the Open Annotation Data Model, especially given the significant overlap between the target communities of Open Annotation and BIBFRAME. We are disappointed that prior efforts to engage with the BIBFRAME community regarding annotation did not yield more constructive results to this stage. We hope that our invitation to discuss issues on the W3C Community Group will be met positively as we feel we owe it to our communities to work towards convergence.