I understand your concerns. Please know that (mt) Media Temple is doing everything we can to assist any and all affected clients. I would like to try to respond to your comments in more detail...
We did not make any passwords "available", but we used to allow customers to see FTP/DB passwords in the AccountCenter in plaintext. FTP passwords were taken out of the AccountCenter at the end of 2009 and DB passwords were removed in early Spring of this year. Those were originally put there as a convenience and based on customer feedback. We have removed them and addressed all of that publicly. Also, as you probably know, passwords that are weak can be "brute-forced", and that happens all the time, on all kinds of systems.
Other companies are mentioned if you look through the links above. Please see this post for detailed information on these exploits and where (mt) Media Temple is coming from:
We are not blaming customers, and to be clear, we are not blaming WordPress either. Also, we have done much analysis on our end and have yet to find any indication that there is a vulnerability in our infrastructure.
On the other hand, via Sucuri.net and other means, we have found that out-of-date software is being used on the exploited customer services and is a source of site vulnerability. Take a look at this list of security advisories for older versions of WP:
Also, this was written by Matt Mullenweg (founding developer of WP):
This article was created to give users detailed steps on fixing an infected site:
If you are an (mt) customer, please open a support request and we can look at the specifics of your account/services.