What are you trying to solve?
I do not believe there is anything related to the current browser session available to the MBO. Perhaps through the bean layers, but that's beyond my knowledge.
You may be able to play around with a relationship to the MAXSESSION table, not sure if these are the same sessionID's you are looking for, but you'd at least get a common session id for the user you could populate on the record, and use as a sub-query.