You can find the patch notes for Hearthstone's 2.7 patch right here, but they didn't quite get all of the changes that were pushed to the game. Here's everything we know about right now:

Features

• Explosive Shot and Swipe have been changed so that they deal damage before triggering on-damage effects. This means that when damaging cards like Imp Gang Boss, the newly summoned minions will not be damaged.
  • Interestingly, Blizzard will still freeze the newly summoned minions.
• The end-of-turn animation for Emperor Thaurissan's effect has been (thankfully) shortened
• Cards will now have text indicating if they were created by another effect (Thoughtsteal, Webspinner, etc.)
• Tracking now has the option to hide the cards so you can view your board before making a decision

Bugs

• The golden portrait for Rexxar (hunter) has lost some of it's shine, becoming less golden
• Healing effects turned into damage by Auchenai Soulpriest will not trigger on-damage effects (Acolyte of Pain, etc.) Blizzard is aware of this issue and is working on it.
• (Possible bug) As before, Tracking does not activate the effect of Chromaggus

Finally, for those wondering, there are no current plans to "buff" the new heroes:

@TheBigWalbowski No current plans, but we're aware of the feedback happening and will discuss it.

— Zeriyah (@CM_Zeriyah) June 16, 2015