Stewart:
Are you seeing this 30 mA of current on the PSEN pin some lengthy time after reset?

I suspect so.

Normally the PSEN is an output and it is typically wanting to be a high signal and go low to do its normal signal. Shorting a High output can lead to rather high currents coming out of IC pins. I would not leave that short on there too long or part damage could occur.

During RESET the original Intel 8051's would tristate all their output pins including ALE and PSEN. I suspect that the ATMEL part does this too. So during the time reset is applied you can normally expect that the current on the PSEN pin will act like the weak pullup current on say a P0 pin.

If you look closely at the ATMEL data sheet they specifically say that the special conditions applied to the PSEN and EA pins for ISP must be removed 24 clocks after the falling edge of RESET. It is most likely that the PSEN pin assumes its normal output mode (where you are seeing the 30 mA) shortly after the time the 24 clock cycle time has expired.

Hope This Helps....
Mike Karas