Microsoft will support the low power ARM architecture in a version of Windows that will hit the market in a couple years.

This has made a big splash in the market, ARM shares went up, Intel slightly down as a first reaction of the stock market. Now many tech savvy people are wondering what the impact of this step will be. First of all, it will open a huge market for ARM and it might also add market share for Microsoft in the low power embedded area.

Nobody can overestimate the weight of existing software for Windows. If hardware using an ARM chip will be able to tap into this software pool, that is an order of magnitude more than all apps for all existing portable solutions today. There is a big difference though between the majority of Apps targeting one hardware platform and the almost endless Windows software being spread around the globe. 

This move is probably too late to make a significant impact to the current generation of tablet devices, lead by the iPad. There is a strong possibility that an evolution of this market will happen in the next couple of years. If Microsoft is able to create a version of Windows that is MUCH more touch oriented for use I/O, it could be an interesting future for all the companies involved. If the user interface will be mostly mouse / keyboard driven, that would be it (the end of it). 

Waiting for more information from the source, namely Microsoft and ARM. 

Just my humble opinion: Microsoft's decision to support another architecture is a little late and will miss a big chunk of the market. Also, it extends the market for Microsoft towards the low end, low cost corner. For ARM the news is better because it opens a door to higher value, high end ARM silicon. More semiconductor companies will adopt the ARM Ax architecture with an outlook to have Microsoft support. So, if I had some extra money to gamble, I would rather put my money on ARM.