A few weeks ago I wrote a .sh script that would check a file to find if there was a new version of the JF roms available. Updating is a pain and I wanted to make it easier. Not knowing Java I decided to write a .sh script which worked but was not very easy to use itself. To make it easier I asked for help here in making a frontend Android app to go with it. Since then, [RiS] has written a nice client that not only does what my script did, but does it without needing my script. The whole process is taken care of within the application. This makes it easier to use, faster and able to do a lot more than my script ever. The app is still in beta at this time but is coming along nicely.
The app name is JFupdater and currently it read a text file on my server (http://android-dls.com/up.txt). The info in that file tells the app if there is a new JF Rom available. I update this file whenever JesusFreke releases a new rom. There are fields for US G1, UK G1 and ADP1 which allows roms for all 3 to be tracked and updated. The version, description, md5sum and a list of mirrors to download. The application checks your phone type (or the phone type you select in the settings) and then checks this file to see if a newer version is available. IF there is it will let you know which are ready for download and give you a download button. Once downloaded the file can be applied by rebooting into recovery.
I believe he is working on making the reboot to recovery/apply update more automates so that after download you would be asked if you want to apply it now, and by choosing yes it would reboot and auto install the update like an official OTA would do.
There is currently a service set that allows you to set it to look for an update ever 1 hour, 24 hours or on boot.
The url where this project is located is: jfupdater.googlecode.com