Over at the Agile Bits blog, Jeff does a great job breaking down the changes to the Dropbox terms of service:

The bottom line is that there is nothing in these Dropbox Terms of Service that gives them the right to do anything with your data that you don’t ask them to do. (The one exception is in the paragraph of the Dropbox privacy policy which states that they will comply with law enforcement requests for data stored on Dropbox.)

I find the take to be pretty accurate, but I would say the bottom line is actually this: don’t keep anything that you don’t want other people to see in Dropbox, unless it is encrypted.