I have spoken to a couple of customers and they are actively deploying WiSMs in their Core switches. Both customers said this was proposed by Cisco directly. I was slightly shocked at this since I have always believed the Golden rule is to keep the Core as that - a Core that switches packets, not a Core/Services node.
In all the design guides I have seen a separate Services module is usually deployed to accomodate these types of services. Why would Cisco recommend deploying WiSMs in Core switches?
I don't want to take it out of context because the folks from Cisco may very well have suggested a solution with a chassis dedicated for the WISMs (my first choice) or placing them in a chassis which wasn't in the core.
You are correct in being skeptical as it's not very good advice taken by itself. It was most likely offered as a way to transition the equipment into the location with the express wish of moving the blades to a different chassis at a later date.
We had actually deployed 2 WiSM's in our core based on budget and recommendations from Cisco. We have sinced purchased 2 6509 WiSM bundles and got those out of the core switches. It's kind of hard to reboot the core when you want to upgrade the WiSM and the version of code on the 6509 doesn't support the version of WiSM code you are deploying...
Plus Cisco really helped us out with pricing on the 6509 WiSM bundles so we could get them out of the core.