After a couple days of inquiries and research (based on rumors floating around out there) and with some help from the great Henry Abbott of TrueHoop fame we have discovered that there was, indeed, a minor rule change put in at the beginning of this season which could affect playoff seeding.
The rule affects the tiebreaker system. It says basically that division winners win ties, regardless of head-to-head record or other criteria. So if two teams tie for 54 wins but one won their division and the second did not (Portland wins the Northwest but Houston comes in second in the Southwest, each with 54 wins) the first team would have the higher seed.
The other tiebreaking criteria follow as stated here, with the exception that the sixth tiebreaker is now point differential instead of points generated.
ESPN.com has an "If the Playoffs Started Today" page here that could be helpful, though the actual matchups are sure to change daily.