I played on this server for approx 1 year and 2 months, and the wilderness is yet to be "Cleaned" up by anyone really, at least not a proper official event that lots of people are in, but like Suppa said, some people can go around and make smaller parts look better, it doesn't really help tho, cause some person just gone come up and mess it all up again, that is the beauty of Multiplayer! :D
I think it was some sort of topic going on a long time ago, it was setting up a huge group of players to clean up the wildy, but this off course never happened cause of the whole breaking houses rule.
The wildy is really not the place to make look good, cause face it, a new member can easily come to the server, make a small little shack and just dig some random holes around for dirt, like every normal MC player would do, then never come back and leave his half finished house, and garden filled with holes behind.
Also, the towns are always a option, go to a town and never look back... >_>