So far, there is no true sense of free speech in SL, but there are many protests anyway. Because Second Life is an environment where the government is also the creator, or god, the government supplied by Linden Lab tends to be without checks and balances, this is a frequent aspect of in-world life that is protested.
Linden Lab simply doesn't have the resources to police the ever expanding world, so they must rely on Abuse reporting instead. One criticism of AR is that Linden Lab only looks at the number of reports, rather than the reason. Because of this confusion many whom consider themselves protesters have been banned from SL as griefers. A griefer is someone who chooses to make life difficult indiscriminately within SL, they usually support no cause other than mayhem. Another type of person similar to a griefer is a troll. Trolls will bother others by trying to disagree or offend them, rather than drop prims that slow down the system.