We are experimenting with Chromecasts and like other consumer devices, wish they worked better in an educational environement.
Our controller is running 6.3.1.12. It is my understanding that 6.4 adds the architecture to make devices like Chromecasts work similarly to how AppleTVs work under 6.3, i.e., they are seen across VLANs and such things.
What we are currently trying is putting Chomecasts on an SSID with a PSK and assigning it to a VLAN based on its MAC address. This VLAN is the same one the client is on, which could be limiting for us if we want students to share their screen as students and teachers are on different VLANs. The clients are authenticated via 802.1x. While this works in general, we are having difficulty with the sceen casting option. Streaming from other apps works fine. When trying to cast the screen, it doesn't find the device, even though on the option to view devices they are listed. I've had a ticket open with TAC for a bit and they haven't been able to reproduce the issue. I talked with them yesterday and sent them backups, logs, etc.
An Aruba engineer was able to reproduce the issue in his lab. And a test I did with an IAP senario running 6.3.x, worked fine for screen casting. My gut feeling is a certain type of broadcast traffic is being dropped. Hopefully, TAC will figure out what the issue is soon as screen casting is a nice and wanted feature.