if you're still sending those off with postal birds to the linden labs?

There is. You can use the bot that is part of Prim Composer. I use it to upload the textures of the Planetarium.

It runs in Linux under Mono too, though takes some extra kicking to do that.

I am doing all of this nonsense on the Mac in any case. I wonder whether it might be easiest to simply write my own.

Mmm... Mono is available on OSX, I think.

You will, however, need to compile libopenjpeg from the slightly patched source in libopenmetaverse kit into native code.

Hm. Thank you for the information, very useful, but I suspect it may just be quicker to make my labels and mass upload them.

It' won't be very practical while there's upload charges.