Their anti-property rights slogans, their disdain for private property, their embrace of socialist and Marxist ideology? See a nice writeup on this point that Cato's Aaron Lucas sent to my Politech list:
Cato is the first place that I visit when curious about the current agenda of the unique mix of libertarian/new world order propaganda. Translating protesters' agenda to "anti-property" *is* pure propaganda designed to scare god-fearing middle class cypherpunks that somehow they will lose some of their property should G8 protesters seize the world government (BTW, it would be interesting to see what is the net worth of cpunkers and how that influences their positions :-) As the word "communist" loses its strength new words are needed to instill fear, and "anti-property" is a nice catchall. It's all in the language. You also enumerate ideologies with implicit assumption that they are "bad". So whatever can be labeled "marxist" or "socialist" is somehow horrible. You don't say WHAT is bad about it, you *assume* that everyone will jump to the bandwagon and agree that it's something bad. Kill the commies. This is a classic propaganda technique. I will not bother citing sources that have exactly the opposite PoV from Cato's - you can look them up yourself. The point of a discussion is not spamming each other with pre-digested, ready-to-wear, downloaded simplifications but to inject some of own experience and induction. Make international calls for as low as $.04/minute with Yahoo! Messenger http://phonecard.yahoo.com/