In North America 1 month is pretty common if you've been with a company for more than a year with 2 months not being uncommon.
I've heard of people being given 1 month of notice of a layoff and then being asked to work that month only once:)
I've been around at a few companies before where cuts happened. The first round of layoffs always got good severance, because the company wanted to make sure that the remaining employees didn't bail... but after 2 or 3 rounds, the jig was up, so the severance shrank from 2-3 months to 2-3 weeks.
I see, this is news to me.
I'm Canadian so I guess the laws can certainly be different, but I was under the impression that 2 weeks was a minimum severance required by law.
I've never seen less than a month, I guess this could be enforced by employment contracts. I know it's been in every one I've signed:)