Let's read InfiniBand's Vision. Whether it can be practically deployed into PC world depends on the price/performance ratio, I think.
InfiniBand was originally envisioned[by whom?] as a comprehensive "system area network" that would connect CPUs and provide all high speed I/O for "back-office" applications. In this role it would potentially replace just about every datacenter I/O standard including PCI, Fibre Channel, and various networks like Ethernet. Instead, all of the CPUs and peripherals would be connected into a single pan-datacenter switched InfiniBand fabric. This vision offered a number of advantages in addition to greater speed, not the least of which is that I/O workload would be largely lifted from computer and storage. In theory, this should make the construction of clusters much easier, and potentially less expensive, because more devices could be shared and they could be easily moved around as workloads shifted. Proponents of a less comprehensive vision saw InfiniBand as a pervasive, low latency, high bandwidth, low overhead interconnect for commercial datacenters, albeit one that might perhaps only connect servers and storage to each other, while leaving more local connections to other protocols and standards such as PCI.
As of 2009 InfiniBand has become a popular interconnect for high-performance computing, and its adoption as seen in the TOP500 supercomputers list is faster than Ethernet. In the recent years InfiniBand has been increasingly adopted in the enterprise datacenters.
for more details, check out this: http://en.wikipedia.org/wiki/InfiniBand