[Brian]

Hmmm... looks like preview release 1 is still up on their website. I downloaded it from them, but their installer fails on my Mac, and manually installing the plugin into the folder I believe it's meant to live in is causing Mail to crash.

I'll see if one of our test Macs does something else when I install it. The first thing I would check, though, is that the "Mail with MailTags" plug in has been re-enabled in OmniFocus' preferences. One possibility here is that the clipper is using our plain "Mail" plug-in instead of the MailTags one...