Digsby Joins the Dark Side, Uses Your PC to Make Money
lifehacker.com
lifehacker.com
http://blog.digsby.com/archives/68
The license agreement is simply worded so as to make this possible.
They also make it difficult to disable the grid computing (It's under "Support Digsby"), and they try to get the user to install six different pieces of crapware.
They do this under the guise of being ad free, but in reality they're advertising by sending out Announcements, which seems pretty shady to me.