It's the 16th most popular user agent seen across the ~60,000 websites tracked by W3Counter. IE7 is the 7th. Dropping support for both will affect 1 in 20 visitors of the 'average' website (your particular audience may vary).
Hospitals and big companies lock down the computers, you can't install anything. If it comes with IE7, that's all you got.
And it's not because of these companies.
E.g. they need to run a specific custom version of SAP (accounting), which on turn crashes if any other browser is present. Upgrading would cost over $30M, so forget it for a while.
Or the hospital needs to validate the hardware + OS + software. Until GE does not support feature X they are stuck with the old version which requires a specific list of software to be installed.
You don't want to hear "sorry about the bad news last week that you have cancer - actually it was just a rendering glitch on your MRI due to the new Chrome version".
So life is a bit more complex than "just upgrade"...
To a degree, definitely. As someone who works in healthcare (both as a practitioner - paramedic), and whose other job is healthcare IT...
I know your example is exaggerated for effect, but there is (or should) be a difference between "general use" PCs in a hospital, and Patient Care / Management PCs (EHR, workflow automation, digital diagnostic imaging, pharmacy and the like). That in itself is a failling of healthcare IT policy.
Sure, your critical systems should all be be "certified", but even that is an area ripe for disruption - witness DrChrono in EHR, and I myself am working, or brainstorming on, better "field reporting" (i.e. 911 response laptops / tablets - most software in this field is horrific for usability, though admittedly there is pretty cool functionality, the ability to transmit 12-lead ECG to the hospital for prepping cath labs is fantastic) - definitely willing to talk to people interested in such a thing.
Edit: as an aside, I'm yet to see MRI software that wasn't driven by a Solaris backend, or even Irix, though that does demonstrate how this area works.
Not a lot, but they are there. I just pulled the Google Analytics numbers for one of my sites and over the past 30 days (3.3M visits) there were 3,003 visits with Firefox 3.6 (1.2% of all FF visits and .09% of all visits).
IE 7 is more common, there were 67,841 IE 7 visits. Worse still is the 12,188 IE 6 visits. Amazingly there were 78 IE 5.5 visits, the web must be a crazy place with IE 5.5.
I was using it this spring (2012) because I had a netbook running Ubuntu 9.04 (9.10 had failed to work properly). But after Google Docs began refusing to let me edit, I finally gave in and upgraded the netbook to 12.04, which has an up-to-date Firefox.
Still, I don't doubt that there are lots of public computers (in libraries, for example) running Firefox 3.6 today. I've seen even older.
Serious question.