Following in the ignominious footsteps of LinkedIn and eHarmony, Last.fm is today disclosing that it too has suffered a security breach that has led to "the leak of some Last.fm user passwords." The note from the company doesn't go into any more depth than that, with a related tweet adding that a security issue is being investigated and advising that, as a precaution, all users should log in and change their passwords. That's sound advice, but what's going on with all these compromised passwords this week?