Making update notification functionality for my themes

the question is simple 🙂 I am making a theme that i will use in lots of sites. So, i don’t want to go all the site and ftp the files every time i fix a bug or do a theme upgrade.

Is there any way i can make a update system like the plugins hosted in wordpress plugin directory.

Looking forward to your answer. Thanks!

Solved:

Thanks Chip Bennett for his excellent link. The update library for themes is now available in that site. You can find it here: http://w-shadow.com/blog/2011/06/02/automatic-updates-for-commercial-themes/

Always consider donation if you see some excellent work that made available for free.

You can also hook into the core update routine. (I’m looking for tutorial links, but my Google-fu is failing me this morning.)

EDIT:

See if this tutorial helps. It explains how to implement automatic upgrades for private/commercial (i.e. non-repository-hosted) Plugins.