There's no streaming from .NET CF. Because of memory limitations, the WCF version for .NET CF/WIN CE has a dramatically abbreviated tool set. The only option in your case for uploading files from a .NET CF device is buffering, though CF might be able to receive a stream (not sure. I've never tried it.) You're limited, too, in your binding options and encryption - SSL won't work, only message encryption.
Here's a link to the subset of features available in .NET 3.5 CF
http://blogs.msdn.com/b/andrewarnottms/archive/2007/08/21/the-wcf-subset-supported-by-netcf.aspx
Good luck ... I was able to get files uploading/downloading to CF, but it wasn't easy.