The problem is that Nikon didn't look forwards they have no logical number progression for their models!!
Call the top model D1,D2,D3 etc - OK
Pro-sumer model D100,D200,D300 etc - DOH!!! What about D101,D102 (they will soon run out of places to go)
Upper consumer model D50,D70,D80,D90 - DOH! What about D200,D201,D202 (if they had kept the D1xx name they could have used D200 for this)
Lower consumer model D40,D60 - Woops bit of a problem here as they merge into the models above!!!
FF model D700 - Where is this one going?
Nikon need to start again with their model names, they have a chance here with the D3000 and D5000. Call the D300s replacement the D7000, the D700 replacement the D9000 and increment them!