Microsoft had previously announced that Windows RT would not be able to run specific software that would enable it for use in the enterprise. WinRT devices are going to run on ARM processors, which is a different line of compatibility to the Intel/AMD lines.
While these two statements seem to be at odds with each other, they are still in line, due to a smart twist played with a single application; the RDP client.
The RDP protocol is normally installed with Windows and it enables remote access to a session running on your Windows PC. By the same token, the client running on your PC, will enable connecting to a remote session on a server or your own work-desktop/laptop where the enterprise software would be running.
With this announcement Microsoft clears the road for a direct attack on the iPad and iOS which has not been completely cleared and was recently deemed to be 10 years behind in security matters.