yes, apparantly there are CB1 and CB2 (cannabinoid) receptors in the lining of the gut. in this way pot not only helps relieve the pain associated with this disease, it actually reduces inflammation.

Crohn's Disease News & Articles

http://www.letfreedomgrow.com/cmu/rheumatoid.pdf (PDF)

there is more scientific and anecdotal evidence out there if you google it.

just keep in mind that pot is not for everyone.. in fact, atm it appears as if i may have to add myself to that list.