I added a 'status' target to the initscript, which gives useful information (i.e. which Thin servers went down if any). I decided to implement it against the output of netstat and not against the running processes as I have at least found one case where an instance was running but somehow not listening to the right socket — But I know this might be polemic/dirty. Read: I'm not uploading this yet, please comment!
FWIW, this patch includes fixing the Lintian warning (init.d-script-does-not-source-init-functions) currently reported for this package.