The --joblog option saves a bunch of useful data that I would like to be able to access along with the saved results files. A natural way to do that would be to add a special value for --joblog (probably ":") that changes its behavior to create a separate log file for each result file. Then when running parallel with "--results out --joblog :", you end up with files like:
out/[arg-value pairs]/stdout
out/[arg-value pairs]/stderr
out/[arg-value pairs]/joblog
The last file contains the single row from the normal (batch) joblog file, e.g.:
Seq Host Starttime Runtime Send Receive Exitval Signal Command
3 : 1357152621.795 0.002 0 0 0 0 echo FIVE
The header should probably be omitted, since this file is meant to be loaded programmatically just like stdout and stderr.
Distributing the joblog alongside the results files like this makes it easier to access useful data like exit value and running time alongside the metadata and output for a particular command.