Although spit does usually mean saliva thrust from one's mouth, it is also short for Spam over internet telephony, the newest form of spam that might gain momentum in the time to come, according to Larry Seltzer from eWeek.

In his article Seltzer ponders over the possible impact of this form of spam, the ways it could be used and what should be done, since the first instances of SPIT have already been documented in Japan:

"In many VOIP networks, such as Skype, calling from one user to another is free. The economics are too inviting for spammers to ignore.
It's not hard to imagine different sorts of attacks that could be perpetrated, especially in combination with a voice response system.
To begin, the spammers could harvest phone numbers the same way they harvest e-mail addresses, but they don't have to. They can just buy online phone books complete with names and addresses."

Armed with such info, evil doers could easily perform frauds, DoS attacks and also generate new spam bots.

But, you haven't yet heard of the worst thing: There is no legislation whatsoever to prohibit caller ID spoofing, data forging and leaving tons of unsolicited voice messages on someone's software answering machine. Oh yes, and there are no anti-spit spam programs yet, and no one really knows how could VoIP communications be secured against SPIT.

So, the brave new digital world is awaiting another spam menace, on top of the unsolicited e-mail, spam fax and cell phone spam messaging.