dbus-0.60-r1 only builds libdbus-qt with the --enable-qt3 option (for qt3 only systems anyhow). just skips qt and apps like k3b miss it.
I'm quite confused on what the issue you're complaining about is... dbus only builds QT3 bindings, which is fine for k3b. the "QT" bindings are QT4 bindings only.
Created attachment 77247 [details, diff] patch for the ebuild
Sorry, for some unknown reason this attachment was placed here. It was thought for Bug 116582.