Tagging output

[Bertelson, Tom (GE, Corporate, consultant)]

I'm migrating some home-grown parallel processing scripts to GNU parallel.  One 
feature I miss from the old scripts is the ability to tag each line of output, 
so you can see exactly what produced them.

A simple example:

$ parallel 'find {} -print | wc -l' ::: /etc /usr/local
    4161
    3792
$ parallel --tag 'find {} -print | wc -l' ::: /etc /usr/local
/usr/local:     4161
/etc:     3792
$

Is there a way to easily do this with parallel?  I cobbled together a "--tag" 
option to get me by (and I'd be happy to share), but I'd prefer to not maintain 
any local patches.