Though its not shown on the OS/2 Device Driver Pak Online site, it appears IBM has an updated Intel PRO/1000 Copper Gigabit driver according to their "Downloads and drivers" search site:
"2005-04-25
OS/2 LAN Adapter Support for Intel PRO/1000 Copper Gigabit Ethernet
http://www.ibm.com/support/...
"
Requires a Passport Advantage subscription for download.