Just read this and it sent shivers down my spine. . .
Summary - virus steals ftp passwords, logs into your websites and injects malware code into all the index and default pages
I've noticed a number of folks in the wpmu dev community have experienced malware injection and hacking issues etc. So if you've got your ftp passwords stored on your machines and especially in your browsers - be warned.
It is inevitable that we can't 100% protect ourselves from downloading something nasty - but we can make life harder for those wanting to steal vital info (passwords etc).
I use http://keepass.info/ (How good is it? I've never had an issue, touch wood) There are lots of password encrypted storage systems - might be time to invest some time in looking for one :wink: