ZeniMedia, id Software’s parent company, have issued a DMCA notice to Google, requesting that all Android ports of Doom, Wolfenstein and Quake be removed from the Android Market due to copyright infringement.  The games themselves are open source, but there are commercial parts of the game, such as some levels and graphics that are not part of the open source agreement.
This in itself is not a particularly surprising scenario, but given that John Cormack, one of id’s co-founders, has mentioned in interviews that he sees mobile gaming as having a lot of potential for the company’s future, perhaps the request is part of a broader plan by id to bring such titles to the Android Market themselves?  Time will tell.
For now, the games are not available on the official Android Market, but are still accessible from some of the alternate markets or directly from the developers in some cases.