At Cisco, I've found that MacBook Pros are the new "hot" laptop for engineers (320 GB, Snow Leopard, 4 GB RAM, instant on/off, etc. versus dog-slow Lenovos with smaller disks, smaller RAM, etc.). And I'm seeing more and more iMacs on engineers' desks.
To be fair, a lot of those Macs have VMWare Fusion (for those things that absolutely require Windows), but I think the overall goal for the company is to get everything running on Cisco's own hardened version of Linux. It won't happen overnight, but the seeds have already been planted.
On the other hand, Cisco doesn't really bad-mouth Windows. It sees Microsoft as a strategic partner.
Leveraging always beats prototyping.