Just found it strange how did you come to the conclusion of a "racial underclass" when there was no mention of it so i was wondering if it is an american thing.
Note: While not as multi-cultural as the US of course, Norway is not exclusively a "homogeneous" society and in fact, I just noted that almost 1/3 of my Norwegian friends are not "Nordic born". You obviously haven't been there if you made that conclusion yourself.
Norway has a very tight pay distribution. Most people earn close to the average/median, and those who earn more get hit pretty hard by progressive taxing.
[1]: http://www.dn.no/nyheter/energi/2010/08/30/her-tjener-renhol...
Though I am not sure I share you opinion on who does the cleaning though. Maybe in a more rural hotel that is the case but whenever I go back to the Oslo especially more recently nearly all the "low rung" jobs are done by recent immigrants.
I noticed hotels seemed to be mostly eastern Europeans, offices a mix of Somali, Vietnamese etc and in restaurants mostly Swedes. There certainly was often discussions in the media of Norwegian youth being too spoilt for those jobs and the country depended on over qualified immigrants to fill these necessary roles. This may also be the case in many other countries.
Keep in mind the cost of living is high in Oslo.