Empower is the name of the type of plug that is used on the US Airbus fleet. UA also uses this type of plug on their widebody fleet in C & F and I'm told it is hit or miss in F on their Airbii. I'm not sure who else uses it but it is one of the more popular standard plug types.

It sort of looks like a what would plug into a cigarette ligher in your car except it has two small recessed pins and clips into the adapter. Many of the power adapters that have an Empower plug come with a car adapter. Usually when you see a company talking about an Air power adapter it comes with a Empower plug.

There are two schools of thought with powering devices in the air. The first is to use a device such as the iGo Juice Universal Wall/Auto/Air Notebook Power Adapter or the Targus Mobile 70 Universal Auto/Air Adapter.

All of these devices have an Empower plug and a cigarette lighter adapter. These devices replace the power brick that comes with your cell phone/laptop/etc. and plug into the device you want to use through the use of an interchangable tip. This is the best option if you are looking to reduce the amount of weight in your carry-on. Unfortunately it is not possible to get an tip for some devices or the tip that is specified for your device may comes with some type of limitation. For example the tip I would need to use with my laptop will only power my laptop and not charge the battery. This is due to circuitry needed in the power brick to enable the recharging.

The second school of thought is to use an inverter. An inverter converts the DC power from the socket back to AC. This let you plug in any device that you have a regular power cord for. A couple of the more popular inverters I've seen are the Targus 150 Watt Dual Outlet Slimline Inverter and the APC Air/Auto DC to AC Inverter. All of these devices have an Empower plug and a cigarette lighter adapter. The downside is that you need to carry with you the power brick for the device you are using. The biggest advantage is that since you are using the actual power brick for that device you don't have to worry about finding the right tips and you get all of the advantages of plugging into a regular outlet.

One word of caution, most of the power jacks you find in the air are designed to put out only 70 watts of power, so if your device draws more then that you will probably end up tripping a breaker somewhere or have other interesting issues.