The 15th release day is definitely different than the 9th (although, yes, VZW still could postpone if they so desire.)
It's different because when the 9th got postponed, VZW apparently told their CSRs to take names / numbers and to notify those contacts of when the release would happen. That has happened across the country, as we know. That is different than the 9th, which was based simply on leaked documents and "sources." The 15th is coming from VZW reps.
Secondly, VZW has already told all of their corp stores TO SELL THEIR STOCK ON THE 15TH. They technically don't need another email, mailer, letter or instructs from HQ announcing this as a release. I think this is why so many stores feel very comfortable telling us to come get our phone that day.
Lastly, the 15th is National Cupcake day, and you can get a FREE ICE CREAM
cupcake on that day! (no, it's not an ICS, but close!) So, of course it has to come out that day!!
Free Ice Cream Cupcake on Dec. 15 - Hey, It's Free!