I recently wrote a client library for Windows CE/Mobile devices, giving them the ability to print to a network printer. The library and article, MobileLPR - LPR client for.NET Compact Framework 2.0 - CodeProject, are usable under The Code Project Open License (CPOL).
The library allows printing to network print servers implementing the LPR, LPRng, and SocketAPI (direct socket connection) printing protocols. LPR and SocketAPI are venerable and widely-used on all major platforms. Since most contemporary printers offer built-in network printing using one of these protocols, this library is a great addition to your mobile developer's tool belt.
I've been going to the Code Project web site for years. It is a nice place to learn and contribute!