In these models, the LED replaces the xenon flashtube that normal alarms use. Since they are new and I don't have access to one, I'm not sure what they're using for LEDs, but it can be set for 15, 30, 75, or 110cd.
These will be nice since the LEDs draw much less current than the xenon tube models (the xenon tube need to be charged to a very high voltage to allow it to flash), and there's less of a high-voltage threat if the appliance needs to be serviced. Anyways, it will be interesting to see what they're like in person.
As per anything else that brags about converting to LED from another light source some research and bit of appropriate consumer skepticism go a long way. I have palm size xenon powered strobes powered by AA batteries that are visible for miles, and there's no concern about high voltage. Also insanely durable. With an LED powered circuit you obviously don't need the voltage that Xenon requires, but you need sufficient LED's to be as bright as you need. 110cd should be easily handled by a couple 3watt LED though.