I'd use the 2.0 APIs, they are days away from getting frozen and will be supported compatibly for foreseeable future.
Details to track here:
On May 22, 2013, at 7:38 AM, John Lilley wrote:
> We intend to use the YARN APIs fairly soon. Are there notable differences in YARNs classes, interfaces or semantics between 0.23 and 2.0? It seems to be supported on both versions.
Arun C. Murthy