Found it:
(b) Aircraft using GPS navigation equipment under IFR must be equipped with an approved and operational alternate means of navigation appropriate to the flight. Active monitoring of alternative navigation equipment is not required if the GPS receiver uses RAIM for integrity monitoring. Active monitoring of an alternate means of navigation is required when the RAIM capability of the GPS equipment is lost.
And:
Any required alternate airport must have an approved instrument approach procedure other than GPS that is anticipated to be operational and available at the estimated time of arrival, and which the aircraft is equipped to fly.
Similar to above, but more wordy. Be careful here, when you choose an alternate, you may not be able to use the approach you want if you don't have an actual ADF or DME installed:
8) For TSO-C129/129A users, any required alternate airport must still have an approved instrument approach procedure other than GPS that is anticipated to be operational and available at the estimated time of arrival, and which the aircraft is equipped to fly. If the non-GPS approaches on which the pilot must rely require DME or ADF, the aircraft must be equipped with DME or ADF avionics as appropriate.
This is new and is why Merit noticed the Alternate mins on a GPS approach. However, most still can't use this (WAAS receivers are still rare):
NOTE-
Coincident with WAAS commissioning, the FAA will begin removing the NA (Alternate Minimums Not Authorized) symbol from select RNAV (GPS) and GPS approach procedures so they may be used by approach approved WAAS receivers at alternate airports. This does not change the above alternate airport requirements for users of GPS TSO-C129/129A, Airborne Supplemental Navigation Equipment Using the Global Positioning System (GPS), receivers.
