I used it a few weeks ago in Ottawa. Sections of it were closed as the ice was in poor condition (not too thin, but too rough for skating).

It was great fun, but wasn't anywhere near as busy as the picture in the article and most of the people using it looked like they were there recreationally.

It does get that busy occasionally. Primarily during Winterlude[1] which is an annual outdoor festival that attracts large crowds. You're right, the primary use is undoubtedly recreational because frankly it's not a great way to commute.

That said, getting around the city on foot or bike can be significantly more convenient during the winter because you can cross the river at dozens of spots rather than having to use one of the handful of pedestrian or car bridges.

[1] http://en.wikipedia.org/wiki/Winterlude

As an Ottawaian I am always a little confused as to why they never run Zambonis along the Canal -- it is because of cost or is it not safe to run these machines on the Canal?

Some people use it to get to work, but most don't. The problem is that it is very very cold here in Ottawa. This morning it was -22 C before you factor in windchill (which would be worse if you are skating.) In that cold it sucks to put on skates, and your face hurts.

It's because they aren't the best for it. They'd require a lot of passes.

So they modified a zamboni! https://www.youtube.com/watch?v=THe4vZ2dVfM

http://www.macleans.ca/news/canada/smooth-operator-2/

Ah, another picture:

http://www.vancouversun.com/crews+clear+snow+then+flood+Ride...

A number of us have actually even used it to skate to work!

I've actually skated to work for years in Ottawa. Shopify always had it's offices close to the downtown end of the canal :-)