According to an NPD report, Ultrabooks are selling well in some segments of the US market. In the Jan-May 2012 period they helped push an increase in sales of the $700 + segment and comprised nearly 11% of that part of the market.Month-on-month growth seems to be strong too.
Soure: NPD
Overall the $700 segment represents 14% of the laptop market but profit per unit and profit margins are generally higher so it’s an important figure.