> is there any other ARM CPU than Freescales i.MX515 that is in the
> range for a netbook?

Qualcomm Snapdragon (upcoming):
http://en.wikipedia.org/wiki/Snapdragon_(processor)
http://www.qualcomm.com/products_services/chipsets/snapdragon.html
http://www.qctconnect.com/products/snapdragon.html

TI OMAP3:
http://en.wikipedia.org/wiki/Texas_Instruments_OMAP#OMAP3
http://www.ti.com/omap3
http://www.ti.com/omap35x

TI OMAP4 (upcoming):
http://en.wikipedia.org/wiki/Texas_Instruments_OMAP#OMAP4
http://www.ti.com/omap4

nVidia Tegra (upcoming):
http://en.wikipedia.org/wiki/Nvidia_Tegra
http://www.nvidia.com/tegra

ST-Ericsson Cortex-A9 implementation (upcoming):
http://www.google.com/search?q=st-ericsson+cortex-a9
Edit: It's the NovaThor U8500 (renamed from Nomadik STn8500):
http://www.stericsson.com/platforms/U8500.jsp

> Is anyone using ARM in a computer today (as the main CPU?)?

Castle Technology in the Iyonix PC (until September 2008):
http://en.wikipedia.org/wiki/Iyonix_PC
http://www.iyonix.com

Advantage Six in the A9Home:
http://en.wikipedia.org/wiki/A9Home
http://www.thea9.info
http://www.advantage6.com/products/A9home.html

TI and Digi-Key in the Beagle Board:
http://en.wikipedia.org/wiki/Beagle_Board
http://beagleboard.org