A short mention on Mibbittomaw on 2011-08-14
It has come to our attention that Mibbit have experienced a security issue impacting (or so it initially appears) their testing servers. This has resulted in a list of plain text NickServ passwords from Mibbit's own NickServ (the one you use if you connect to irc.mibbit.com) being made public, as well as a small section of private logs and some internal server details of the affected equipment. There's some more information on their own blog.
As I'm sure many of you have been aware, Mibbit hasn't been available for use with freenode for quite a while now so the issue will only indirectly impact freenode users when the password they use for their NickServ is the same as it is for elsewhere. Therefore freenode staff are recommending that anyone that has used Mibbit's own NickServ should ensure that their password is changed to keep your account secure.
Of course, it's always good practice to change passwords periodically so you may wish to take the opportunity to do so as a matter of course.