As i know, the thing that is coming behind Microsoft's
announcement is sometimes much pompous and
opinionated. Microsoft has announced that CLR is Open
Source and is available to all third-party industry.
As we refer to the past, Microsoft's policy is
strictly tight with its support of existing customers
and businesses to enable well trading!. I mean holding
support of COM, DCOM and COM+ is a strategic policy
for Microsoft since its huge society of Customer
Businesses and Organizations needs that to stay
alive(Thanks for Mr. Rajaeeian has mentioned about
it). You can see such non academic developments in
other areas, like Virtual Machines when Microsoft's
operating systems switched from MS-DOS to GUI Windows
OS. Finally, Microsoft's notice on availability of CLR
as Open Source, has targeted third-party industry to
expand their support of CLR as what has been done to
JRE. How much Microsoft would be successed in real, we
should be waiting. Howevere Microsoft will accept any
offer in this area with shouts of welcome, indeed.