A warning sticker at the bottom of the box notes that it will cause "some of your extensions and/or themes to stop working until they are updated."
This is common. Some of the add-ons I depend on, like the Google Toolbar, don't always follow a Firefox update right away.
But this list of incompatibilities carries just one name -- Microsoft .Net Framework Assistant 1.0.
Interesting. Everything else is expected to work with the new Firefox except .Net, so it's ready not just for download but ready to be pushed out with notes to all clients urging them to get it?
It's a nervy move, one certain to win applause from open source advocates and Microsoft haters. How ordinary users-on-the-street who consider Firefox "just another browser" will feel is a story well worth following up on.
So let's follow up. You there. You look like a user, on a street. Are you going to rush in where Microsoft angels fear to tread? I know I am.