Yes, I agree. Announcing to early stops customers from buying other Verizon phones as well.
Also, Verizon dosn't announce a phones release date until they are virtually assured (99.99+%) that they can release the phone on that date. If they announce to early something could happen that might delay the release date. Just think of the posts here if Verizon announced a date 30+ days in the future and then the boat from China sank and umpteen million phones went to the bottom? I can see it now, " Wah wah, they promised, yada yada, class action, blah blah, going to AT&T, whine.... etc."
Here another leak, (Not official) from UnWiredView:
Verizon Motorola Droid Bionic shown with September 8 release date and $299.99 price once again Unwired View