Indeed. Weather modification has been going on perfectly openly for over 60 years. Nobody has ever denied this, or tried to keep it secret. It's be widely reported and discussed in the mainstream media.
The problem is that the "chemtrail" conspiracy theorists tend not to have heard of it, and so react with great excitement whenever they hear of it being "admitted" - not realizing it's simply new to them, not actually new. See:
http://en.wikipedia.org/wiki/Cloud_Seeding#History