pagerank was implemented as an iterative mapreduce on classic hardware (and sibyl later adopted this model, using MR as an engine to do what is really an HPC job). Not sure I really consider it HPC, more like high throughput. HOwever, the MR approach worked really well when google was scaling super-fast in the early days; if they'd chosen to solve the problem using MPI and infiniband on expensive SGIs, they probably wouldn't have become the company they are today.

agreed about infiniband and sgis, but numerically approximating the principal eigenvalue of a large sparse matrix seems solidly in the core of traditional hpc. btw pagerank predates mr by several years