Those four are
* Kapsch
* ITRI International, Inc
* Cohda Wireless and Cisco Systems Inc.
* Savari Networks
The original news came from: http://www.its.dot.gov/procurements/roadside_safetypilot.htm
From the news last Oct. there are 8 firms participated the test of DSRC equipments organized by US DOT: http://www.its.dot.gov/press/2010/hia_device_award.htm
* AutoTalks Ltd
* Cohda Wireless
* Cohda Wireless/TomTom
* Denso International America, Inc.
* DGE Inc.
* Industrial Technology Research Institute
* Savari
* Siemens Government Solutions.
This list could serve as a good reference but not complete supplier list of DSRC/802.11p equipments.
