I've been with LiveJournal for years (and, right now, I'm not going anywhere) without having any Unsolicited Commercial Emails (UCE) issues with them.
Today I got UCE from Project Gizmo who power the default Windows application for LJ Talk - LiveJournal's Instant Messenger.
Now, I don't recall any opt-in or opt-out checkboxes in the process. In fact, the screen grab alongside this shows the download form. You simply grab the .exe and log in.
LiveJournal do say that they'll share some data with their partners. That'll be how Project Gizmo managed to translate my log in into an email address.
Brad Fitzpatrick, of course, left LiveJournal and Six Apart to join Google (not Facebook; which is the fashion currently) and there were rumours at the time that Six Apart/Danga was sinking into dark times. I would imagine he would be less than happy with the idea of LiveJournal passing details on for an UCE blast.
What's Fitpatrick doing now? (Probably) deeply involved in Google's forthcoming social networking projects.