FireFox made it version 1 finally. A lot of people are advocating switching to using it instead of IE in order, primarily, to avoid the continuing stream of security issues with IE. I think there is some wisdom and foolishiness in this. If it's just you and your system, no problem, use whatver browser you want. But in an Enterprise, IE is deeply entrenched with group policy, deployment and lockdown infrastructure, and of course Microsoft scripting/Active X technology.
My biggest hope is that this really stokes the fire at Microsoft to get their game together around browser technology. They've made a mess of it and don't really seem to have any clear vision about what their doing with IE except trying to get the next patch out. If they do have such a notion, they haven't communicated it well.
The other big deal is that having another browser out there that is widely adopted DRAMATICALLY increases development costs of websites. If you want to market to those Firefox users, you have to create your websites such that they work and look good in both IE and Firefox. Tables, colors, borders, a gillion things are rendered different. Just browse around with it for awhile and see what I mean.So, this has got to get factored into budgets right away, and I'd bet that it's been widely ignored.
From a security perspective, it won't be long till major problems are found with FireFox as well. How many, how serious, and how frequenty - remains to be seen. The better it is, the better IE has to become.