Does the getwork id value do anything?
If you are talking about the Bitcoin API, getwork only requires data field, which is a place to put your solution.

However, I do believe that you are talking about the id field of a JSON RPC command. It is used to identify a response to a given request. Generally, it might not be the best place to put extra information. There are already a few extensions to the getwork protocol that you might want to use instead.