Exactly like Linux. From Wikipedia:

"In the United States, the name Linux is a trademark registered to Linus Torvalds. Initially, nobody registered it, but on 15 August 1994, William R. Della Croce, Jr. filed for the trademark Linux, and then demanded royalties from Linux distributors. In 1996, Torvalds and some affected organizations sued him to have the trademark assigned to Torvalds, and in 1997 the case was settled. The licensing of the trademark has since been handled by the Linux Mark Institute. Torvalds has stated that he trademarked the name only to prevent someone else from using it."

Bitcoin development is centralized too in a way (it's easy to find and cease and desist the devs), so are the exchanges and merchants. There is more chance of Bitcoin being trademarked and abused by a hostile/greedy entity than by whatever community entity is willing to do it. Maybe the FSF could take it under its wings or something (not sure if they do trademarks as well besides copyrights). It certainly will be more expensive to ligitate after the fact, and depending against whom, more or less successful.