A few years back, it looked like the Internet gurus were poised to stop most spam, or at least spam that pretended to be from legitimate domains. Similarly the proposals, known as RMX or SPF, would have taken a big bite out of virus distribution and "phishing" (e.g. those eBay and Paypal password scams).
The idea was to have each ISP check that the mail actually came from where it said it did -- if it said joe@aol.com, then it really ought to have come from an AOL server, not some ISP in Minsk.
Fast forward several years and we're still waiting, as technical cat-fights and overreaching by an unnamed software monopolist have tossed the whole thing back into committee. Here's a great article on the blow-by-blow details on the delayed approval for SPF, RMX and/or Sender ID.
According to more recent reports, all have made up and work is proceeding.
Hopefully so, and soon.