[caudicus]

I stumbled into the about section, and in there they mention they're using a fleet of 500 volunteer ADS-B receivers networked to a central server, and they actually just pick up on planes with ADS-B transponders (more common in Europe than the US, it seems) - http://www.flightradar24.com/about - so it looks like they're not aggregating official/moderated data feeds or anything.

[chmars]

FlightRadar24 nevertheless follows the FAA 5-minute rule. In other countries, there is even a delay of 10 or 15 minutes.

In Switzerland, the federal aviation authorities tried to impose a delay as well. After a wave of protest pointing out the absurdity of such security through obscurity – you can see aircraft in the sky after all! -, a delay is no longer necessary and you can check in real time which aircraft is flying over your head at the moment (if equipped with ADS-B).

[cjrp]

I'm not sure it follows the 5-minute rule for non-FAA data. I've watched, for example, an Emirates A380 go over my flat (near Heathrow) almost exactly as it's passing on the FlightRadar24 map.

[cjrp]

They recently added FAA data to the US map (go to Settings on the left and tick "Show FAA traffic").