Our RTM build number of .NET Framework 4.0 is 4.0.30319.1 . After appyling "Visual Studio 2010 Service Pack 1" to your Visual Studio 2010, you will see that some DLLs in your .NET 4.0 upgraded from 4.0.30319.1 to 4.0.30319.225 .

For example check your C:\windows\Microsoft.NET\Framework64\v4.0.30319\clr.dll's version (for x64 machines) or C:\windows\Microsoft.NET\Framework\v4.0.30319 (for x86 machines) by right mouse clicking and selecting properties. The "Details" tab will show the "Product Version".

You may ask yourself "Ok I compiled my app with VS2K10 SP1. But shouldn't some things also be updated on my server which will run my new app?". You're right about asking this question. The answer is here in this KB article titled as "Update for the .NET Framework 4" in http://support.microsoft.com/kb/2468871 .This update needs to be applied to your server. But before deciding to apply this update or not, you should check another new article on http://support.microsoft.com/kb/2520479  titled as "Web services may fail on Microsoft Internet Information Services (IIS) 7.5 and Windows 7 Service Pack 1 with .NET Framework 4.0 due to extensionless URL handlers"