Wireless sensor network?

If I want to make a sensor network I will usually use the arduino board with the sensors connected by jumper wires to the arduino and then implementing a radio/wireless connection between my arduino and a web-server or other arduino board depending on the case. This is the most common scenario, I think.

What I'm looking for is that if I want to distribute sensors in different sites at my home (let's see in each room), then according to the previous scenario, I would buy an arduino for each sensor, sense I cannot connect sensors to the arduino without jumper wires.

My question is if there any kind of sensors that have builtin powering system and wireless connectivity so it will be easy to distribute it in different places without connecting it to the arduino by jumper wires? or if there's any other solution.

Thanks in advance.

Look at Moteino and JeeNode. They do exactly this with Arduino processors.

There's lots of commercial systems out there. I think X10 has sensors. They aren't cheap. Much more costly than an Arduino at each node.

For semi-permanent installation, don't use jumper wires. Use a proto-shield and solder the sensors onto the shield. The JeeNode system has simple plugs to connect sensors to the processors but you usually end up with something that looks like a proto shield.

For permanent installation, custom PCBs are surprisingly cheap and effective.

As I thought, eventually it seems there is no way to connect stand-alone sensors without helping of microcontroller as a processing and/or connectivity power. I checked out the Moteino and JeeNode projects, they are relatively cheap and serve my purpose, especially Moteino.

Thanks MorganS for your help :) .