The Ultrabook or the MacBook Air really isn't something new, the MBA was just the first to get it right
The picture above is not Sony's latest product. It is their Vaio X505 from 2003. PCWorld has an excellent article giving advise to PC laptop manufacturers. Yes, Apple did not invent the ultra thin laptop. What they did in 2010 with the second generation MacBook Air was made it relatively affordable, putting it into a price range comparable with their MacBook Pro's.
How light? My own standard would be 11.6 inches at not more than 2.5 pounds, 13.3-inches at not more than 3 pounds, 14 inches at not more than 3.75 pounds and so on.
How thick? A bit under an inch is fine. About 0.8 inches would be a nice thickness. I would not mind if my MacBook Air was a bit thicker. Too thin is actually awkward to carry in hand. Weight counts more than thickness I think.
What I don't need. I can live with just 2 USB ports (make one 3.0 please), a jack for a mic and earphone, and a HDMI port. For wireless WiFi and Bluetooth, with a 3G/LTE or Wimax being an option. A dock can be provided for those who need more ports.
How many of us still use the optical drive, and how many use it on the road? Drop the optical drives. We can always buy an external drive. I really don't need the SDCard slot. Between Mini-USB to USB connectors and Bluetooth I really never use it. It is time to ditch the LAN and phone line port. I am sure some may miss these features, but really a WiFi router is really cheap these days and dial-up internet is really a thing of the past. Instead of adding these legacy devices, just drop the price a bit.
What I want. Solid State Drives and passive cooling (ARM anyone?).
Not in aluminum please. Aluminum looks nice but is easily scratch. I take of my wristwatch when I use my MacBook Air, and no I do not want to put it into a protective case or wrap it in plastic. It is really time to do a lot of research on a more suitable material. Carbon-fiber would be nice, if there could be a cheap way to mass produce it.
Price. 11.6-inches at US$700, 13.3-inches at US$900. Well, at least if you want to keep me from buying a MacBook Air. The Samsung 900X3A is interesting, but really the only premium brands in the laptop market are Apple, Vaio and the "ThinkPad" label. Yes, many of us are willing to pay for the lighted Apple on the lid. If it says Samsung, HP, Dell, Acer or Asus on the lid, we do expect it to be cheaper.
My 2-cents.