Postini as we've know it is shutting down. Google is forcing their Customers to move to Google Apps. I have several Customers who have been using Postini for multiple years each and I'm expecting a rough patch when we start being forced to "transition". As of the last "webinar" I attended w/ Google people there still isn't feature parity for the end user-facing portion of the service for those of us who still have on-premise email servers.
Yes, I read that page before they shut down my account. They sent it to me repeatedly, saying I needed to move everything to Google Apps. Completely ignores the fact that some features in Postini are not available in Apps; that Apps is several times more expensive; and that Apps includes a range of apps that are completely unneeded (if I wanted Apps, I would have signed up for it instead of Postini to begin with).
Edit: I should rephrase: they did not "shut down" my account. They just informed me I would no longer be eligible to renew my account when my subscription expired.