A: Virtualization on its own isn't the only driver toward converging Fibre Channel's glass cabling onto Ethernet's copper, but it's arguably one of the larger factors. The simple truth lies in the complexity of routing large quantities of cable around a data center. In the old days, physical servers might see a bonded pair of two Ethernet cables for TCP/IP networking, and another bonded pair of fiber-optic cables for Fibre Channel traffic.
A virtual host might add additional networking for migration, management network communication, as well as for additional networks that virtual machines might need. Add all these networks together, and that's a lot of cables in each server.
Performance improvements for Ethernet itself have also driven this round of network convergence. With 40GB and 100GB connections (nearly) ready for production use, the potential to combine all kinds of traffic atop a single bonded pair of interfaces becomes desirable—as well as cost-effective long-term.