SevenCubed - 9:29 pm on Oct 10, 2012 (gmt 0)
The intended purpose of their recommendation is valid but the version they are using looks like it may be out of date.
Your example (or rather Microsoft's) may be obsolete...
<meta http-equiv="content-language" content="en-CA">
... but the newer version is not
<meta name="language" content="en-CA" />
The old example above might even pass html validation, or maybe not, but it will not pass section 508 validation if I remember correctly. I'm shooting from the hip here so I could be wrong.
I use the "<meta name="language" content="en-CA" />" version for all my docs.