By expanding its line of AMD-based offerings, IBM is following the success of high performance Opteron blades and servers from its main competitors, HP and Sun Microsystems, as well as the success of IBM's own LS20 blade.
Even though IBM was talking Opterons this week, it's still planning on offering Cell processor-based systems in the not-too-distant future. Presumably, these machines will be specifically targeted to the HPC market. In anticipation of this, other HPC folks have been busy investigating how to use the Cell processor most effectively for supercomputing workloads.
For example, Jack Dongarra and his team at the Innovative Computing Laboratory are continuing their work on exploiting single precision arithmetic on the IBM Cell processor.