Ah, that's interesting. I find it very useful to ensure that user-generated text doesn't break out of an HTML or JavaScript string
You get the same effect if you use the numeric character reference as described in the document I previously linked to, or avoid delimiting attribute values with single quotes and use the more conventional double quotes.
Are you aware of any browsers that don't support this entity in HTML?
Not off the top of my head, but using it in text/html is non-standard, and its easy to avoid.