Since it is effectively a free and anonymous hosting service (files hosted can be shared publicly via HTTP), I can easily imagine it being used for distributing malware.
I wonder how effective this sort of attack would be against Dropbox in the future.
If the block is solely based on malware distribution then Facebook would have suffered the same fait ages ago.
Amisdst all the data Google stores it should be clear that Dropbox isn't a random site freely dropping malware around the web.
If it can't figure it out then a good old fashioned human should.
Screenshot: http://bit.ly/4xZpA8
They aren't free and anonymous, are they? The free and anonymous part tends to be important to malware distributors. Exploiting existing servers is one way, but free sites are also used quite heavily.