tl;dr:
   "myth: true concern in a tin-foil-hat tone"
   "fact: here are some quote with vague legalese from the bill"

if you really want the facts without the tin foil hat tone, http://news.cnet.com/8301-13578_3-57580268-38/cispa-permits-...

"Rep. Alan Grayson, a Florida Democrat, proposed a one-sentence amendment... to secure a warrant ... that House Republicans "wouldn't even allow debate on requiring a warrant"

"CISPA is controversial because it overrules all existing federal and state laws by saying "notwithstanding any other provision of law," including privacy policies and wiretap laws, companies may share cybersecurity-related information "with any other entity, including the federal government." It would not, however, require them to do so."