I don't think what you want is possible, you can turn on 'nice' urls' (like on the ez.no site) but not item number only. Maybe you could rewite the 'nice' url mapper to use the item number instead of the title of the document. This would require some coding though.
In 3.1 url mapping will be available, so that might help a little as well.
Tony
Tony Wood : twitter.com/tonywood
Vision with Technology
Experts in eZ Publish consulting & development