When I click on "Share Screen ..." in Finder, Screen Sharing opens but does not open the window in which I would normally see the other computer's screen.
This is on my iBook G4. All works fine the other way around using my iMac G5.
I have the same problem as you, although my iMac can see my MBP screen but not the other way , unless I add a new account - then it works but that's not a preferred option as I'm sure a new account would require Time Machine backup to start all over again?
I have tried repairing permissions with no luck, it does however work over iChat, and I can connect to the iMac through normal finder file sharing just not Screen Sharing.
Screen Sharing works from my G5 to my MacBook, but not the other way. Very annoying. I got it to connect once by manually entering the G5's local IP, but only once.
Ironically, Jaadu still works fine from my iPhone...
I dont think its the remote desktop client. If you create a second account and test it though there you will see it works still. I a security issues that can be fixed in your Key Chain follow the link.