There is a similar question for 3.5 here:
Is there a built-in zip library in .NET 3.5?
that speculated that 4.0 would have it, but I can\'t find any info abo
You may have already moved along, but ZiP API is added in .NET 4.5
http://msdn.microsoft.com/en-us/library/system.io.compression.ziparchive.aspx
go nuts.