It's not acceptable in the UK: http://www.telegraph.co.uk/news/uknews/2659948/Tesco-to-ditc...

Hardly sounds definitive. From your link:

"There is a debate about whether the word should be 'less' or 'fewer'," a campaign spokesman said. "Saying 'up to ten items' is easy to understand and avoids any debate."

and

A Tesco spokesman said: "The debate about what is right has been going on for years now, and I still don't think we know if 'less' or 'fewer' is correct."

That’s odd. I know highly literate people from all of the above, and I’ve never heard any of them misuse less.

Usually the highly literate folks misusing less are from Germany, the Netherlands or Scandinavia. It’s jarring when I hear or see it in otherwise erudite discourse.

Now, I know many native speakers of English in the US and various commonwealth nations that are unaware of the distinction. So I suspect you’re right on the larger point that this particular persnickety rule is dying in the vernacular everywhere. But I’d love to see your source for this rule not being universal in formal speech or when written.

My 'source' was merely hearsay :)

It seems there's a wikipedia article on the dispute: http://en.wikipedia.org/wiki/Fewer_vs._less

Which mentions the 'rule' started to get pushed around in the 1800s, though 'Less has always been used in English with counting nouns.'

I suppose we'll always be stuck with this ambiguity in English since there's no formal authority to tell us how we should speak/write.

From my own observations, having grown up in Australia and since moved to the US, I must say the common practice is notably different, I almost never heard anyone say fewer in Australia, but have noticed that many Americans (like the poster here) seem to be on a crusade to ensure less isn't 'misused'.

Canada.