It does indeed look like it's broken in the latest versions of Chrome. I believe
this is the root of the problem.
Rumor has it Chrome is working towards Services integration, though, so perhaps in the future we'll be there!
Actually, it's there now. Highlight the URL, execute your "OmniFocus:Send to Inbox" shortcut, and you _should_ be good to go.
Edit 2: And you can even select text, now, from the actual email. This is news to me. :)