The highest I've seen that I can trust is 6000 mcd. I've seen one seller on eBay offering 7000 to 9000 mcd with a 30° beam angle. Although he's a reputable seller, I don't always trust specs on eBay.
I've already seen 16000 mcd white LEDs with a 15° beam angle. The same chip in a 30° package would translate to roughly 7000 mcd based on relative brightness of current parts so maybe the specs I mentioned above are reliable.
When we start seeing white LEDs produced with Cree's new Xthin chip (18mW min), then we should have about twice the brightness we do now for all beam angles, and a luminous efficiency of over 60 lm/W. This would translate to ~12000 to 15000 mcd for a 30° beam angle. I have no idea when this is going to happen.
