here's a link to the grower of these hops. http://www.yakimachief.com/hopvarieties/mounthood.html
From what i can gather they are another american grown hallertau type hop which is from german origin.
Many purist and most home brew stores in Australia are of the thinking if you want such a hop then use the real thing so they will only stock german hallertau. Another example is american grown willamette which is very similar to fuggles so most stores in oz will simply only stock fuggles and say willamette is inferior.
This would not be really the case in the US but it is indeed the case here in Australia with home brew stores.
Sorry iam rambling on here but i think you get the idea.
MT hood equals a noble type german hop, maybe not the same hop at all but the german type hops would be what you would use to swap the mt hood for.