I found this on a site called LEDs magazine. Obviously it will be a while before they are commercially available and I also wonder what the output at lower colour temperatures would be but is does seem to show that things are moving at a good speed.

Cree R&D result breaks 200 lumen per watt barrier
04 Feb 2010
Cree is claiming a new R&D record for a white high-power LED.

High-power LED manufacturer Cree claims to have set a new laboratory record for a white, high-power LED of 208 lm/W. Just two months ago, Cree reported an R&D result of 186 lm/W. The 208 lm/W LED produced 208 lumens of light output at a correlated color temperature of 4579 K. The tests were conducted under standard LED test conditions at a drive current of 350 mA at room temperature.

As acknowledged in Cree's press release, this level of performance is not yet available in Cree’s production LEDs. The company says that this R&D result passes a "significant milestone" within the solid-state lighting industry, as well as demonstrating Cree’s "relentless drive" to increase the performance of its LEDs.

“We have now broken the elusive 200-lumen-per-watt efficacy barrier for a single white power LED,” said John Edmond, Cree co-founder and director of advanced optoelectronics.

“This is a result of improvements in blue [chip] optical output power, lower operating voltage and higher conversion efficiency. We continue to push the envelope in white LED technology to enable the highest efficiency white lighting products in the marketplace.”

Worth noting that this is almost a third of the way towards the maximium possible efficiency...

http://en.wikipedia.org/wiki/Luminous_efficacy

"Photopic luminous efficacy of radiation has a maximum possible value of 683 lm/W, for the case of monochromatic light at a wavelength of 555 nm (green).

"White" light has a maximum possible luminous efficacy of more like 300lm/W depending on your definition of "white" IIRC, so 200lm/W is pretty damn good.

Rgds

Damon

After much googling I've just ordered these to try..

5W GU10 LED 400 Lumens warm white for £13.

http://www.amazon.co.uk/Interlux-trade-efficiency-Replacement-halogen/dp/B004KRB7XS/ref=sr_1_1?ie=UTF8&qid=1314868727&sr=8-1

Discovered these after ordering the above..

http://www.amazon.co.uk/LIGHT-ENERGY-SAVING-WHITE-BRIGHT/dp/B0056AQ666/ref=sr_1_50?ie=UTF8&qid=1314869188&sr=8-50

5W GU10 LED 400 Lumens warm white for £11.

Sorry all I know is they are the 5050 form factor. Have started new thread here..

http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=7769&page=1#Item_1