Holly "Windstalker" Longdale mentioned it in this week's EQII Insider QA Livecast, then tweeted it yesterday afternoon:
Gear Up, Level Up promotion extended thru the end of July! Also, Double XP for Adv, AA, TS experience this Fri noon - Sun 11:59pm PDT!
That's double tradeskill, adventure, and AA experience from July 11, 2014 at 12:00 noon Pacific time through Sunday July 19, 2014 at 11:59 pm. Note that this doesn't include guild experience, but Holly said during the livecast, "We might do Double Guild XP the weekend after next."
You can read more about the Gear Up, Level Up promotion on our EverQuest II site.
UPDATE: This just in from the official announcement: "Experience bonuses do not stack. All Access members will get 100% adventure, AA and tradeskill experience bonus instead of 25% experience bonus for those experience types specifically."