In addition to applying to any player who's reached level 50, the 30 days of free game time will now be applied to the account of anyone who has reached Legacy Level 6 in the game. This condition requires that a player has unlocked his or her Legacy at the end of Chapter 1 and then achieved six levels across any number of toons (Legacy XP is shared across an account).
Another change to this promotion is that players have over a week to hit either one of these goals. Players now have until 1:00 p.m. EDT on April 22nd to achieve either level 50 on a character or Legacy Level 6 on an account to receive the free month of play.
Following news of yesterday's Legacy promotion, the SWTOR forums exploded with discussion over the topic, with the main discussion thread reaching over 250 pages on the subject.