I've seen a couple servers have this. I dont know how to do this myself, but I would like to have the bots ride horses and spawn messages for "Rare spawn" type bots.
These features will be in V1.9.1 which should be released fairly soon.
A few people are testing that right now; I guess you've been on their servers.
Horseback navigation is terrible right now, where obstacles are concerned, so I'll want to improve that before release.
Stay tuned. ;)
thanks so much!