Based on posts in the Mt. Whitney facebook group there are LOTS of folks religiously checking for cancellations daily/hourly/minutely especially this year now that it's more 'known' how the system works.
Also for the previous poster - the old 'walkup' permits that weren't reservable at 6 months out are now available online 2 weeks (14 days) from the start date online only. And frequently get snatched up right away at that 14 day out date for more popular trails.
=)tif
