The KDE3.5 repository has been migrated to a new team PPA, and in the next month or so I will be heavily modifying the PPA that you are currently using.
I have updated the instructions on http://apt.pearsoncomputing.net to reflect the new team PPA, so please update your system with the new repository information as soon as possible. Be sure to update the GPG key as well, by following the instructions under "Add the GPG signing key".
This will not affect your current software installation--the binaries have been copied directly from the existing PPA with no modifications. I am only requesting that you update the repository locations in an effort to prevent future problems, as the old PPA will become a development/testing PPA in the future.
Thank you, and I hope you enjoy your KDE3.5 installation!
Timothy Pearson KDE3.5 Maintainer
announcements@trinitydesktop.org