Ghostcrawler asked the Warlock community for suggested changes, and a couple have already been implemented.
• Metamorphosis (http://wotlk.wowhead.com/?spell=47241) won't dismiss your existing demon. It also gives you 600% armor bonus, up from the 360%. You can also now cast spells while in demon form.
• Corruption will now be instant cast! Improved Corruption (http://wotlk.wowhead.com/?spell=17814) will increase damage by up to 20%.
• Ruin is being moved to a lower tier so more Warlocks have access to it.