Since the last two weeks, I have been getting 5-6 spam and phishing emails to my unique dropbox email address, so they must definitively have a leak on their hands. Found various reports on twitter, too.

I've also seen similar leaks from linkedin (obvious, since they acknowledged their hack), everydns, the nokia development forums (another obvious one that was acknowledged as compromised), namecheap.com and uneetee.com.