Pretty much what it says on the tin - I'd love to use Glimpse as it covers the majority of our stack (knockout, nHibernate, signalR) but we use OpenRasta for our web framework.
I've searched around and can find little - does anyone know of any plugin?
As a sidenote - would writing one be very involved?
I don't know of an OpenRasta plugin for Glimpse.
The Glimpse side of plugin writing is very easy, so any difficulty would stem from OpenRasta's extensibility and hosting story. Unfortunately, I don't know enough about OpenRasta to speak to that.