When will motherboards based on ARM processors be available?

My use is for standard corporate desktops. Required applications for users in this small business are Firefox, OpenOffice and IM. Decent graphics will be necessary, in order to support streaming media. I'm not talking anything special here, just your basic desktop. In other words, Ubuntu on ARM should be perfect.

The IA architecture is three decades old and showing its age. With Google and Ubuntu joining Debian as active development partners for the ARM platform, this seems to be the direction to look for the next decade. I even read a journalist speculate that Apple would move Mac to ARM.

Unfortunately, there's nothing in the technical or even trade press to answer my question. Can anyone provide any insight as to when I'll be able to buy an ARM-based motherboard through the online retail channel to build desktop machines? What are the potential pitfalls of being an early adopter?