Bitmap's release relationships script does a single webservice query to fetch release information, e.g.
http://musicbrainz.org/ws/2/release/6f3cbf73-3ad3-4454-8af6-fad34e8e1b5f?inc=recordings+recording-level-rels+work-level-rels+label-rels+url-rels+work-rels
Prior to the schema change release, this query included work iswcs - after the schema change release, it no longer does.
http://codereview.musicbrainz.org/r/2158/
http://codereview.musicbrainz.org/r/2158/