Re: @ scatter
"Thankfully halogens only last 1,000 hours also so they'll disappear just as quickly as GLS lamps once the transition starts."
My last set of MR16 and GU10 incandescent purchases were 10,000 hour jobbies. They lasted about 5 years before I replaced them with CFLs and then LEDs (Tesco's leds/cfls have been reliable, ones from other sources (I'm looking at you B&Q!) have not been.)
I finally got irritated enough with the RF and infrared hash emitted from all the ES and BC CFLs around the place that I changed them this year.
16W "corncob" leds easily outperform 21W ("100W equivalent") CFLs and apart from not having that pesky 30 second warmup period have a better colour gamut too.
The externals will be replaced with leds when the CFLs in them start to die (which should be next year) and at the same time I'll be considering "upgrading" to the robot ones which track heat sources as the existing cheap fittings are starting to craze due to UV exposure. I've seen the robot ones in action and you'd be amazed how fast a prowler can run if the light swivels towards him- and stays pinned on him as he moves. The only current issue is the cost.