[SugarJ]

Rosetta is a CPU only application at this time. There are other projects that utilize the GPU as well. From the BOINC Wiki:

Projects with NVIDIA applications:

• GPUgrid.net
• SETI@home
• Milkyway@home (Double precision GPU required)
• AQUA@home (cuda offline)
• Lattice
• Collatz Conjecture
• PrimeGrid (AP26)

Projects with ATI applications:

• Collatz Conjecture
• Milkyway@home (Double precision GPU required)
• DNETC@Home

Edit: Supposedly AQUA@Home just released an OpenCL application, I'll have to look into that.