I've found a friendly giant! I even helped him out with some wolves (Like he needed it)

http://www.youtube.com/watch?v=A6vmNeGI3mA&feature=youtube_gdata

I'm not sure which makes certain ones hostile. Maybe area they're located in?

They are protecting their mammoth cheese! ;]]

XDD kill em all!! like i do. Wont stop until every giant is dead...and mammoth.

First giant I found I assumed would be friendly from the videos I saw of them.. so I walked right up to him and he destroyed me

Can anyone confirm if there are any TALKING giants in the game? Would be cool to get a quest off a giant.

Its their territory usually.

Often they will warn you before you get too close, but I guess some players just charge about.

I came accross an NPC on his own quest to give a painted gift cow to the giants. So to make peace that they wouldn't destroy his farm. Love it.