Google Polyline Tool
You can get this code using Mercurial by doing:
hg clone http://bitbucket.org/James_Snook/googlepolyline
or using this download link.
This is a C tool for encoding and decoding a Google Polyline. The C files for encoding and decoding the polyline are in the PolylineC folder You can use the C Code in a project by including the polylineFunctions.* files, and the AppendableDataStore.* files (the polylineFunctions.* files require the AppendableDataStore code. The makefile will build an executable called PolylineTool which takes input from stdin and writes a polyline to stdout. The input needs to look like the text in the ExampleCoords file.
The code in the googlePolylineTest folder is an iPad test app this is what is currently being used to test the polylineFunctions code.