The AgileZen C# SDK by Ian Davis allows API access, providing code to communicate with the API. AgileZen offers authentication, formatting, filters, enrichment, and pagination in its developer site. Additional information at http://dev.agilezen.com/
The trouble with building mobile computing applications is that end users have little tolerance when it comes to how they expect those applications to behave. Never mind the fact that mobile applications are amongst some of the most challenging to create; the second somebody has a less than optimal experience they're off to another application. Needless to say, that puts a lot of pressure on mobile application developers.
Chaos usually reigns within most application development organizations; a situation that in many ways has been made all that much worse by the simultaneous rise of agile development methodologies and mobile computing.