The Edge folks (namely Joey Snow) sat in on the SQL Server 2008 shiproom on the day we RTM'd. You can view the video here. A few interesting things to share.
During a release shiproom happens every day. Each team across SQL sends at least one representative. Depending on where we are in the release cycle the agenda and mood of shiproom is different. For example, in the end game we're in what we call "Ask Mode". This simply means that each and every fix that is checked in must get approval. That's right, every single fix. This probably sounds like a lot of overhead, but that's somewhat the point. SQL's a big product and it takes time to slow down the ship. Every code change carries risk. The purpose of Ask Mode is to slow down code churn and ensure we apply a consistent triage bar.
The final day, sign off day, is very fun and festive. I was there the day we signed off on Yukon. The champagne was flowing and people were hugging and shouting. It was a lot of fun. For Katmai I was in a conference room one floor up preparing for the press conference call publicly announcing SQL2K8 RTM. The shouts of joy coming from shiproom were deafening.
The sign off paper is ceremonial and doesn't carry any operational significance. Joe Wilcox thought it was funny that people were signing a piece of paper. The actual sign off on the release is digital and doesn't require each team to sign off. For SQL2K5 we simply went around the room and each team said "<Team Name> is a go!" It doesn't matter if it's a verbal sign off or a written signoff, it's fun and cool to do it.