I agree completely.  There are two "killer apps" for grid computing: data and compute.  We should, by all means, aim to construct standard interfaces for these applications.  (Having said that, I should also point out that these "wheels" have been reinvented since time immemorial...)

 

However, failing to construct a common credentialing solution will result in, as you mention, "islands of grids" for any application standardization effort.  And if islands-of-grids is an acceptable ends to our means, I have to question what we are doing in these working groups: we can simply refer the reader to a specific instance of middleware architecture documents (or implementation, even) as the standard for that "island".  Problem solved.

 

-Duane