I could cope with the screen being at 90 degrees but co-ordinating moving mouse horizontally while seeing cursor going 'up' was rather headache inducing for me (like left/right turns using a mirror, but worse!)
Ctrl-Alt- Up arrow works too. It's probably the question I answer most often on MN - I did once suggest that they put the solution at the top of the Geeky stuff topic page.
Toddlers do it by banging their fists down each side of the space bar - one gets Ctrl & Alt, the other lands on the arrow keys & the screen turns 90° (left/right arrow) or 180 if they get the down one.
With older children, like the junior school ones I teach ICT to, it's usually because they get Ctrl-Alt-Del wrong when logging on, or because they think the computer has frozen.
(Until I saw it here, I had never come across it before... says something about the increase in use of laptops, where the graphics seem to have been improved significantly... 'cos I have sometimes helped out on a radio show from Chicago that covers PC/Mac problems - and in a few years of that I have not heard of it, nor in previous 5+ years of PC support.)
It's not just laptops webdude - you can do it on desktops too. My sister uses it a lot - she's a professional translator & she has a monitor which swivels to portrait orientation, which is better for long documents - she's had it for at least 5 years.
Yes, I remember there have been swivel screens, but it's surely down to the graphics adaptors and the facility seems to be more common in laptops, AFAICS, or maybe it's because I'm not the type to spend 150 to 300 pounds for a graphics card to add to my PC
Well it worked on our previous suite computers, which were Elonex Prosentias bought in 2005, with Intel GMA 900 graphics. I don't know a lot about graphics cards/adaptors etc, but those machines were pretty crappy at handling images generally - the HP 7900s we have now are so much better.