The Leopard problem was twofold, one with the installer (which we're still looking at) and one with EigenD itself which prevented it from running. The second problem has now been fixed, so if you do install EigenD from the command line with 'sudo' omn Leopard it should now run just fine. The installer problem is a permissions related issue (on Leopard, and only on Leopard, the installer no longer does the right thing and this is not an easily fixable problem post install) and can only currently be fixed by running it from the command line under 'sudo'. We currently have no idea how to fix this issue as it seems to be a problem in Apple's newer installer.
We're having an internal discussion about whether or not to continue support for Leopard, as it's proving very troublesome and all the developer tools effectively don't support it properly anymore. Despite it not yet being officially declared 'end of life' by Apple, it's looks like it certainly has been unofficially discarded by them (I don't think they're doing security updates for it anymore for example). We'll keep you posted as to our decision next week, and in the meantime if anyone has very strong feelings about it, please let us know.
John