Yes, I would assume that anything that functions as a tablet (touch screen without a keyboard) and a traditional laptop like (with a keyboard) would be considered to be a convertible.

If you are considering buying one make sure to spend some time with it, PC magazine in their review

http://www.pcmag.com/article2/0,2817,2410808,00.asp

had a couple of deal breakers for me. I'm not sure they have not fixed them by now or not. One was as a laptop, the screen was not adjustable, it had only one position. That just won't work on an airplane, every time the yahoo in front of you moves their seat you need to adjust the screen, and when used as a laptop there are delicate cables exposed.

Granted, at this time we don't know if the Microsoft Surface has the ability to adjust the screen or not, though most of the reviews do like the kickstand to prop it up.