Lpc2000

I have been reaching about 90 uA for both battery and supply

Yes you can wake from sleep via the RTC as well as external interrupts - this works well. The uarts dont work 
in power down but you can use a transition on uart0 to wake the processor. switch port to interrupt mode - power down and wait for transition - swich port back to uart - watch for malformed characters in the Uart.  
The processor takes about 30 usec to wake up. The wake up process consumption can use more that the processing you do while awake. Expect about 110 uA if waking every second

as bob says: watch for pullups in some pins - these can hog power if your not carfull

see my postinin the files section.

Owen

Has someone experience with the standby current of the LPC213x and LPC214x derivates
and can tell me what to expect what to expect when the core is in sleep mode with and without the RTC running.
Is there also possibility to wake up the core with a timer running in the background and what would be the expected
stand-by current in that "sleep mode" ? Are there graphs available ?
The aim is to build a small POS printer on ZigBee and power management with a portable device is always an issue.