[tomku]

No, it's part of the Machine. Direct quote from the Steam Machine page:

"Steam Controller's wireless adapter is built right into Steam Machine for direct pairing. "

It has dedicated hardware for pairing with Steam Controllers without needing a puck adapter plugged into a USB port.

[cassianoleal]

They said Puck integration, not wireless integration.

I promptly admit I may have misunderstood something though.