http://www.washingtonpost.com/wp-dyn/articles/A52274-2001Jun11.html

The Supreme Court ruled today that at least some forms of hi-tech police surveillance require a warrant, as they are subject to fourth amendment protection. As the Post article states, this isn't really a "blockbuster" case, but it is an important protection against Big Brother type technologies. What's most important about this ruling is that it covers surveillance technologies that don't yet exist.