@Outofscope:

Cydia uses Debian's well-documented APT repository format, which you should find ample documentation for. However, I understand that the documentation may be too extensive or unclear in some regards, so I am in the process of writing up a little article/guide. I should probably stop procrastinating and get it done today. In any case, while you're waiting for the guide, take a look at the following repositories in your web browser (these are currently the 2 default repositories bundled with Cydia):

http://modmyi.com/repo/
http://apt.saurik.com/

as examples of working repositories, and I'd also like to point out that we are in the process of creating a tool to automatically create a Cydia-compatible repository from an Installer Repo. The ModMyI repo was generated in 29 seconds from its Installer counterpart. We call this tool the Debicizer (thanks to Erica Sadun for the catchy name ) and it will hopefully be a cross-platform open-source tool, with plans for a Mac GUI Repository Creator in the near future.

Cydia and Telesphoreo are under active development, and they will only get better over time, so keep your eyes peeled for further updates!

Note: for those of you interested in the debicizer project, the current project location is:

http://debicizer.googlecode.com