I would really like to see Avidemux supporting subtitles.
I usually just want to merge/cut video files. All operations should be performed on subtitles as well and then saved in the resulting file.
You are not alone:
http://avidemux.org/smif/index.php/topic,17402.msg78874.html#msg78874 (http://avidemux.org/smif/index.php/topic,17402.msg78874.html#msg78874)
http://avidemux.org/smif/index.php/topic,16996.msg76181.html#msg76181 (http://avidemux.org/smif/index.php/topic,16996.msg76181.html#msg76181)
but so far:
http://avidemux.org/smif/index.php/topic,16996.msg76193.html#msg76193 (http://avidemux.org/smif/index.php/topic,16996.msg76193.html#msg76193)