kdepim needs libical, available from here: http://sourceforge.net/projects/freeassociation/
It's a relatively small parser for PIM files.
You will also need libcaldav and libcarddav, both of which are available on the Trinity home page under "Related Projects".
Are these new dependencies? Or options?
What benefit do they provide? For example, I have no need for most of the bling some people think they need with email. I use a very basic KMail. Do I need these added dependencies?
A heavily patched libical was originally included as part of the kdepim source code. For the Trinity project this was split into an external dependency, as other programs also use libical and there was no more need for the KDE-specific patches to the upstream code. This is a dependency that will need to be filled even for basic functionality.
libcaldav and libcarddav are for the new CalDAV and CardDAV resources, for korganizer and kaddressbook respectively. You can disable them, but you will lose interoperability with newer PIM suites such as Google Calendar and Zimbra.
Tim