CISPA is similar enough to the recently defeated SOPA and PIPA bills, both of which had good intentions for copyright holders but severely missed the mark in regards to privacy and censorship.
The 28 companies are:
AT&T
Boeing
BSA
Business Roundtable
CSC
COMPTEL
CTIA - The Wireless Association
Cyber, Space & Intelligence Association
Edison Electric
EMC
Exelon
The Financial Services Roundtable
IBM
Independent Telephone & Telecommunications Alliance
Information Technology Industry Council
Intel
Internet Security Alliance
Lockheed Martin
Microsoft
National Cable & Telecommunications Association
NDIA
Oracle
Symantec
TechAmerica
US Chamber of Commerce
US Telecom - The Broadband Association
Verizon