Personally, I'm not really a fan of IP cameras. They're pretty notorious for leaking their images to anyone with access to the network. So if they're running on our WiFi (which is only marginally secured), people may be able to swipe images from them without authorization.
I prefer good old fashioned CCTV-style cameras wired up to a DVR like what we have for the 3-4 cameras that are currently rigged up.
These are WIFI enabled cameras with pan/tilt and 2 way audio (at least for windows). They have an integrated web interface and both an administration mode and a user mode. They can be programmed to run a pattern and only record when there is motion. The output can be directed to a server of your choosing or to the cloud.
I am thinking these could serve a dual purpose. The user mode could be used as Tele-presence devices. The device logs who connects to it and that can be sent to a server too. We can scan the logs for who is connected and put the name up on a display at the front of the room.
My next idea for added security? Dogs and Bazookas!