The Bush administration objects to the creation of an ".xxx" domain for adult-oriented websites. Here's a snip from Declan McCullagh's report for CNET:
Michael Gallagher, assistant secretary at the Commerce Department, has asked for a hold to be placed on the contract to run the new top-level domain until the .xxx suffix can receive further scrutiny. The domain was scheduled to receive final approval Tuesday.
"The Department of Commerce has received nearly 6,000 letters and e-mails from individuals expressing concern about the impact of pornography on families and children," Gallagher said in a letter that was made public on Monday.
Link, and here's some related ICANN correspondence: PDF 1, PDF 2, PDF 3.
Related links on Politech:
