So what did the QA team do, this day after?
- went out to lunch together
- cleaned up the wiki page to reflect the release as complete instead of in progress
- burned archive CDs of the release
- archived the test plan (including test results)
- answered questions from dev, product management, deployment, sales, etc.
And that's about it.
If your team has worked hard through the release, there's probably a mountain of work still to be done. But take a day - just one day - as a breather. There needs to be a lull after release so you can release all the stress.
In the end you'll gain more for that than you'll lose with a few hours of inefficiency.