Sadly, Conglomerate has very little documentation at the moment, both user and developer documentation is practically nonexistent. There is, however, an introduction to conglomerate's architecture available, which should at least be of interest to potential developers.
In addition, there are some more philosophical and forward-looking documents here, such as Structured data and the death of WYSIWYG, originally written for Advogato, and our response to the frequently asked question about editing code with Conglomerate.
Conglomerate was originally built using the GTK+ toolkit, and for these historical reasons it is now built on top of the GNOME 2 platform. We intend for it to interoperate well with both the GNOME and KDE environments, and encourage you to send bug reports (and fixes!) if you find any problems with this. (Indeed, the lead developer of Conglomerate has run KDE as his main desktop for some years) We would like Conglomerate to become a standard fixture on all free desktops.
As another historical note, Conglomerate was originally built on top of the Flux library, although that dependency has long since been removed. This legacy might show through occasionally when looking through CVS archives.
And there's always the mailing lists if you have specific questions, or want to help out.
If you want to request CVS write access, see this document.