Ultrabooks are not netbook "toys" (priced under $500 using an Atom processor). There is one Ultrabook that has been on the market since July of this year...it's called an Apple MacBook Air. There's no question that MacBook Airs sell well...we'll have to wait and see if consumers can be convinced to purchase similar hardware from a non-Apple company.
The 2 main shortcomings of Ultrabooks vs. a regular notebook (as I see it) are that there is no built-in optical drive (does anyone still use these? -- you could still hook up an external one for the rare times you need it) and you are limited to Intel's graphics. So clearly it's not targeted at power users or gamers, but then that's what...5% of the consumer market at most?
Personally, I would go for a notebook (Nvidia/AMD graphics, high-res large display), but the rest of my extended family would go the Ultrabook route (possibly even netbooks, ick).
Source:
http://en.wikipedia.org/wiki/Ultrabook
First phase (Q4 2011)
Thin – less than 20 mm (0.8 inch) thickness[6]
Lightweight – less than 1.4 kg (3.1 pounds)[7]
Long battery life – 5 to 8+ hours[8]
Mainstream pricing – under $1,000 USD (for base model)[9]
No optical drive
Use flash-based SSDs[10]
Use CULV (17 W TDP) Intel Sandy Bridge mobile processors
Core i5-2467M (1.6 GHz)
Core i5-2557M (1.7 GHz)
Core i7-2637M (1.7 GHz)
Core i7-2677M (1.8 GHz)
Use Intel's graphics sub-system HD 3000 (12 EUs)