Evernote has recently improved their APIs ...
http://www.evernote.com/about/developer/api/
... and has set up a service for surfacing database integration of third party apps to users ...
http://www.evernote.com/about/trunk/
... so good Evernote / Omnifocus integration should be much more possible now.
Personally, I'm in the process of trying to migrate EVERYTHING into OmniFocus and Evernote, so strong integration between the two would be an enormous boon to me.