The Denver Post reporters John Ingold and George Plavin either don't know what "astroturfing" is, or don't care to correct leftists for using the term incorrectly.  In their report on the Denver Tea Party, they quote Mike "The Headless Chicken" Huttner, as deriding the Tea Parties:

"The tea parties are the latest version in a months-long campaign against change, organized by right-wing think tanks and lobbyists who have done well over the last eight years under George Bush," he said.

He pointed to a number of national conservative political groups listed as sponsors on Taxdayteaparty.com, including FreedomWorks and Americans for Limited Government.

But of course, publicizing events isn't astroturfing. 

Astroturfing is when paid activists pretend to be unpaid volunteers or "men on the street."  It's when ACORN members pretend to be "outraged citizens" stalking AIG employees.  It's when people are paid to spam websites with comments, or when the Pew Foundation finances a campaign finance reform campaign, and then conducts a poll showing increased interest in the subject.  It's when DNC employees photocopy petition signatures and then report the number submitted in triplicate. 

In short, it involves deception, and hiding one's involvement in a campaign in order to make it look popular.

This isn't random name-calling, this is an attempt to deprive the language of a useful term for the sort of thing the Left excels at by changing the definition to any sort of organizing.