Since you know everything. The day Lion was released on the App Store we had over 150 installs. The following day we had literally hundreds of help desk calls over things being broken.
That could have been dealt with before hand - knowing the date of release is irrelevant if all you have to do is send out an announcement telling people to hold off until you have certified it internally. If you do any sort of formal support for end users you should have these policies. Make it clear long before a new version comes out.
Again, how is knowing the date going to help you if you don't either have policies in place like this.
At our office we do not allow people to just install a new OS (even if they own the box) unless we certify it. We tell them what we support and that's that.