Well, I was just trying to avoid duplication of data, and aiding people to
get really only what they need/want rather than everything.  Its not
perfect, and the overhead of multiple requests is probably worse than one
request for more data since we're dealing with pretty small files.

The usage that I was designing for was basically people polling
http://uec-images.ubuntu.com/query/released.latest.txt , and determining
if they were out of date based on that data.  If so, they would do further
queries to figure out what actions needed to be done.

That said:

http://uec-images.ubuntu.com/query/released.latest.txt
gives you a row for each unique build in the released 'stream'.
The 'released' stream contains builds labeled 'alpha-*', 'beta-*', and
'rc', and 'release'.  The other stream is the 'daily' stream.

The primary key for a build is a combination of the 4 fields:
  suite, build_name, label, serial.
ie:
  hardy  server   release  20100827

That line above tells you that you can find download data for that build
by reading
http://uec-images.ubuntu.com/query/<suite>/<build_name>/<stream>-dl.txt
http://uec-images.ubuntu.com/query/hardy/server/released-dl.txt

That file has 7 fields
  The first 4 of the key (suite, build_name, label, serial)
  Followed by arch, path, and 'suggested name'.

So, by walking each row in the released.latest.txt, and getting the
appropriate released-dl.txt, you can get the data you want.

Ie, this will get you what you wanted:
  burl="http://uec-images.ubuntu.com/query"; str="released"
  wget -q "${burl}/${str}.latest.txt" -O - |
  while read suite bn lab ser; do
    wget -q -O - "${burl}/${suite}/${bn}/${str}-dl.txt" ;
  done

Alternatively, the data on uec-images is available via rsync.  So, the
following will also get you want you want:
   rsync -a uec-images.ubuntu.com::uec-images/query .
   cat query/*/*/released-dl.txt