Yes, where do we stand with PM-ing all users one way or another?
I agree that the message, since it will be the same, can be stored just once (centrally), only a 0/1 for each user would have to be created in the DB (which is a whole lot easier than storing the entire contents of the message once for each user).
The admin would be able to create say 12 messages of this type (this could be a admin setting variable), and every new one thereafter would overwrite the oldest previous one (message #13 would overwrite message#1 including the 0/1 - so that message would then automatically disappear from everyone's inbox regardless of whether they have read it or not).
Most importantly the message will look like any other message, so in effect this feature will really look like getting a regular PM from the admin.
