This doesn't look very encouraging, no updates since February!
Anyway, I too am on Leopard 10.5.2 and EyeTV 2.5.2. I can see that if I login to IceTV Remote the programs are scheduled there, so that suggests the widget part of it is working correctly.
On the EyeTV end of things, an EPG update request works as expected, and shows my account expiry date, so that suggests the EyeTV to IceTV communication is working (at least to a point anyway).
However, if I attempt to update via Remote Scheduling nothing appears to happen. Other parts of the preferences page seem to give some sort of feedback, eg under the account details it's showing my expiry date, while the EPG section shows the time of the last successful update. However under the remote scheduling section it says "EyeTV will check only when you have a network connection", which seems to suggest it's having problems seeing the network. Maybe there's some other setting required there? If the EPG updates are working, I don't quite understand why remote scheduling isn't simply accessing the network in the same way?
Any hints gratefully received.