Well, without any further details, there isn't really much to say here. For example, what makes you think that it was even Geeklog that was hacked? Some add-ons or other scripts that you have on your site may have caused the problems.
And it's also possible to install Geeklog in ways where it can be hacked easily (e.g. not changing default passwords, not following the installation instructions properly, ...).
If you can provide any information to substantiate your claims, then we would like to hear about it. Please send any details you could provide to geeklog-security@lists.geeklog.net and we'll look into it (see
this page for further information).
bye, Dirk