Sen. Conrad Burns (R-Mont.) and Sen. Ron Wyden (D-OR) introduced the CAN-SPAM bill on April 9 (S. 877), "to regulate interstate commerce by imposing limitations and penalties on the transmission of unsolicited commercial electronic mail via the Internet." See the Burns press release here. The two Senators also co-sponsored the CAN-SPAM Act of 2001 (S. 630).
Also see one of my previous postings on spam here for links and statistics about the public response to spam and related institutional costs.