Couple ideas I've been thinking of.
Things I've been thinking about - I'd love to try them myself, but it's not like UnrealEd is any closer to a Mac compatable version...
• Prison Laser Tag, a modified shock rifle would be available only while in jail. This rifle does no damage, but reads to a hitcounter that's available on the HUD. So, if there were three guys in jail, they could shoot at each other, which would not get you frags, but simply add to the hitcounter. Perhaps then the person who has the highest number is first in line for arena combat.
Once jailbreak occurs, the laser tag gun goes away and is replaced with the standard shield gun/assault rifle combo.
• Door Close, perhaps little more than a "it might be interesting if", but when playing jailbreak, you've usually got a few defenders standing around guarding the door, someone comes in, initiates jailbreak, teleports back (if the mutator is active), and those who are in jail are now free. But what if, in addition to the jailbreak token, there was another token, close by, which would close the doors? If left unattended, a team would never truly be jailed, because they could escape the moment they were locked in, but if attended well - one might be able to close the doors before all of the inmates escaped.
Problem being that this would require editing of the maps to create this new token, but still - something to think about.
...that's all I got for now.