Verisign submitted a very nice presentaiton with pictures showing its proposal for monitoring all parts of the network including ISPs, hotels, cafes, universities, etc.
http://gullfoss2.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6516088289 You can search for all other submissions on the FCC web site under the ECFS system using the proceeding number RM-10865. Verisign's is not the only proposal. There are many alternative ways to assist law enforcement, some of which are much less expensive and possibly more effective.
