Our MIS folks have used this device called "Netbotz" for a couple of years now. I have to say, especially in the later versions, that I am quite impressed by their capabilities including motion-detection cameras, alerting, and all the environmental probes you mentioned. Those little things have saved our necks quite a few times. The PoE thing may not be there yet, but I really don't know, best to contact Netbotz to inquire about this type of power requirement. http://www.netbotz.com/
pj