Taws-gps
 

JAA / FAA mandates TAWS Jan 01, 2005 and Mar 31, 2005 respectively.

Anyone knows if GPS position data feeding to the TAWS / EGPWC is a requirement?

To me it seems flawed to have this nice EGPWS display on the EFIS if the position is not GPS updated, especially in an area with limited radio nav update.

GPS is not required per se - the NAV data can, and often does, come from the FMS (which could be DME/DME or worse) to drive the Terrain function. Don't forget that any Enhanced GPWS (to use what is now Honeywell's (ex-Sundstrand) proprietary nomenclature) still includes a normal GPWS that must not be effected by any of the "Enhanced" additions.

Some EGPWS units in addition to having a terrain database also include GPS for position information, and either display on a MFU or on the wx radar, these are generally for turboprops and smaller exec jets.
Really nifty kit.

Lots of good info with downloadable pilots guides at:

http://www.egpws.com/

(by the way, if you try to download the pilot guide, transport types download "Mark V and VII").