Ahh, the scientologists have another one. I guess they are the ones that will live through the apocalypse. I highly doubt that their bunkers could help their lost souls, though. On Wikipedia:
According to the CST, the purpose of the base is to provide storage space for an archiving project to preserve L. Ron Hubbard‘s writings, films and recordings for future generations. Hubbard’s texts have been engraved on stainless steel tablets and encased in titanium capsules underground. The project began in the late 1980s.
The base includes a number of dwellings and the archives themselves, the latter in a network of underground tunnels. The base also has its own private, concrete airstrip, the San Miguel Ranch Airport (NM53); it is not shown on FAA sectional charts or in navigation databases by the owner’s request.
An aerial photograph showing the base’s enormous Scientology symbols on the ground caused media interest and broke the story in November 2005. According to a Washington Post report, the Church’s first reaction was to attempt to suppress the information:
The church tried to persuade station KRQE not to air its report last week about the aerial signposts marking a Scientology compound that includes a huge vault “built into a mountainside,” the station said on its Web site. … Based in Los Angeles, the corporation dispatched an official named Jane McNairn and an attorney to visit the TV station in an effort to squelch the story, KRQE news director Michelle Donaldson said.
The church offered a tour of the underground facility if KRQE would kill the piece, the station said in its newscast. Scientology also called KRQE’s owner, Emmis Communications, and “sought the help of a powerful New Mexican lawmaker” to lobby against airing the piece, the station reported on its Web site. 
The huge symbols on the base, distinguishable only from an aerial view (35°31’28.56″N 104°34’20.20″W), are specifically those of Scientology’s Church of Spiritual Technology. Former members of the Church have said that the symbol marks a “return point” for Scientologists to help find Hubbard’s works when they travel here in the future from other places in the universe.
From another blog:
Did the government get a secret underground base in return for cutting Co$ the biggest tax break in history? What kind of underground base could have been worth that? Is the government “sharing” the land with an organization the IRS now calls a “religion”????????? How is that constitutional?
This is beyond insane. Seriously…it depresses the hell out of me, also.