I have been looking for custom zombie maps that have gobblegums in the map. I have found one map, Fortress, but can't find any other maps with GG. Any maps you know off the top of your head, with GG, please post.
As "therocksays02" says, gobblegums are definitely a work in progress, but once there's a fully functioning script for it I'm sure it'll be widely used.
Nightclub is a WIP, not posted on this site though. It has gobblegums. Gameplay can be seen on TheRelaxingEnd's YouTube channel with "Rayzorback" in the title.