Here is a good summary via our good friends at Mantex:
Neologism Ahoy!

http://en.wikipedia.org/wiki/Internet_sock_puppet

Would you know a sockpuppet if you saw one?
And even more, what would it have to do
with astroturfing - if anything?

I came across a whole slew of new terms
recently - all to do with creating bogus
identities and fake opinions on line.

A sockpuppet is a false identity used for
purposes of deception in an Internet
community. The sock sets up stupid Aunt
Sally comments which the puppeteer (in real
persona) then demolishes to gain credit.

Astroturfing gets its name from the fact
that it is pretending to be 'grassroots'
support for something - but in fact it's
a fake construction by stealth marketeers
and public relation wonks. Read it all here.

http://en.wikipedia.org/wiki/Internet_sock_puppet