WCF Service for adding Sharepoint users?

Currently we have an application that is written in .NET 3.5, which we are planning on upgrading to .NET 4.0.

Is it possible to create a WCF service that could make use of SharePoint 2010 API to create Sharepoint users by calling that service from .NET 4.0 application? What sort of issues do you think i may run in to if we upgrade, as Sharepoint 2010 work开发者_JAVA技巧s with .NET 3.5 and not 4.0?

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Yes, you can use .Net 3.5 web service in your .Net 4 application . You will have difficulties with DTO types, but if you use the properly serialized xml data then, should be no problem.