Michael O'Leary said:
			
		
	
	
		
		
			But since they don't burn out as quickly ....
		
		
	 
I don't buy into that, on average use simulated in a lab they last 10 times longer than a regular incandecent, however I've got one incandecent on a dimmer in my house that refuses to burn out and a couple in lamps, and since I bought the place I've replaced several CFLs that aren't even on that much. 
CFLs seem to burn out faster the more you turn them on and off, and incandecents seem to burn out after a long time burning, and while turning them on and off causes them to pop, if they haven't reached critical stage it doesn't seem to hurt them as much as CFLs. Fun fact, the pop and bright flash when an incandecent burns out is actually a very tiny fusion reaction.
I change a CFL once ever month or so.
Anticdotal evidence... so 
Besides I'm not a believer in CO2 causing environmental problems anyway, though I'm very concerned with releasing toxic liquid heavy metals into the environment and the circuitry uses some pretty exotic chemicals and toxins that just aren't present in regular old incandecents.
[/hijack]
I think lumens and Wattage are both important specs on the bulb, lumens to provide actual output, and wattage to show consumption, so you could come up with an efficiency unit by specifying lumens/watts.
Since they are pushing us to rely more and more on producing our own off grid power to supplement what we consume and reduce our consumption so that our self produced power provides a large a percentage of our total use as possible, which only makes sense to increase effective ROI.
so lumens might not be the measurement you are most concerned with if you have a target of providing say 50% of your own power, you may be more concerned with how many watts you consume.
If a carbon tax ever gets rolled out this would be a big issue as well.
that might be the angle the EU is going for... many of them have carbon taxes, maybe they are trying to hide/protect the ammount people are paying extra by making it harder to get the most efficient products. Nah too tin foil hat.