As far as multi-threaded performance goes... IBM's compiler supposedly reconfigures single-threaded code into multi-threaded code. I don't know how well it works at this point, but it'd be quite the boon to development.
Regarding Cell yields... it's The Inquirer. Believing their non-sourced stories is like believing The Weekly World News.
I'm no fan of Sony, but I believe the Inq was referring to the move to 65nm away from 90nm (at which IBM has previously stated yields are good) which, naturally, is something Sony needs to do ASAP to avoid bleeding to death on hardware costs.