You also need to consider the time it takes to distribute .NET 4 β it wonβt be immediate, with the exception of the developer community. If you are building a redistributable application for .NET 4, potential customers will need the latest installed runtime. This is not so much a server-side issue, but even that can be a problem.
If you are planning an application that will be released some time after the release of .NET 4, this may work for you. Not knowing how MS plans to distribute the v4 runtime, I suspect it will be some time before it is wide enough to be attributable.
Grant palin
source share