Nat on O’Reilly Radar does it again, this time explaining GData from Google in terms I get:
GData is just Atom/RSS for reading, Atom Publishing for writing, and A9 stored queries for searching.
Interestingly:
There’s a huge move within Google away from SOAP and even REST-style ad hoc APIs and towards GData instead.
and
They’re building APIs to your Google-stored data via GData
Lastely the architect of GData is the same chap who did Microsoft’s HailStorm.