Patrick Eddington has a good summary:

"Unlike the House Judiciary Committee bill passed by that body in December by a 35-2 bipartisan margin, the new bill 1) does not mandate a warrant before FBI personnel can sift through the FISA Section 702 database for information on U.S. Persons and 2) still allows federal law enforcement agencies to buy data on U.S. Persons from data brokers--no warrant required.

The bill also allows for FBI agents to go through the Section 702 database for information "relevant to an existing, open, predicated full national security investigation.""

There were reports that intelligence agencies will have a secret briefing for Congress this afternoon, although Eddington now says it might not happen. In any case, a vote is expected Thursday.

If you're in the US, now's a critical time to contact your legislators. This issue crosses party lines, so even if your representatives usually don't listen to you, they'll be paying attention to the number of calls they get on this one! Eddington has instructions on how to do it via Congress' site, or Demand Progress has a handy web page.