Can I pass non-string to WCF RESTful service using UriTemplate?

As dthrasher mentioned, move id to the query part of the URI. This worked for me:

[OperationContract]
[WebGet(UriTemplate = "/foo?id={id}")]
string GetFoo(int id);

See “URI scheme” on wikipedia for more info about the different parts of a URI:
http://en.wikipedia.org/wiki/URI_scheme