Given the dramatic increase in thru hikes on the JMT documented below, I can't say that I blame the wilderness officials for tightening up the process. This will make it significantly more difficult to hike the full JMT southbound from Happy Isles to Whitney Portal, especially for those who do not have reservations. The new rules go into effect for reservations made on Monday, February 2. This means that they are NOT in effect tomorrow - the last day to reserve permits under the looser old permit regime.
http://www.nps.gov/yose/planyourvisit/jmtfaq.htm