So Cisco just picked up IronPort for a cool $830 million. IronPort operates a system it modestly calls “the world’s largest email and Web threat detection network and database.” Basically, it’s a blacklist that helps keep out the Internet’s known bad guys.

Why care? Take a look:

• Worldwide spam increased from 31 billion daily messages in October 2005 to 61 billion per day in October 2006.

• The average spam size has grown from 8.9KB to 13KB, a 46% increase.

• Bandwidth used by spam increased from 275 terabytes per day to 819 terabytes per day, an increase of nearly 200%.

(Source: IronPort survey, November 15, 2006)

All this points to two obvious conclusions. First, spam is placing a growing stress on the Internet. Second, unless you love those pitches for Viagra, the notion that “all Internet content is equal” makes about as much sense that pitch you just got for a penny stock that’s about to return 300% next week.