So first there were quests to get into Serpentshrine Cavern and Tempest Keep. Then Blizzard created "attunement scrolls," which dropped from the bosses of each and allowed guilds to attune other players or alts who'd missed out on the action so far. And then Blizz removed the attunements entirely. So what happened to the quests and the scrolls?
All we know about the quests so far is that Blizzard has promised to add extra steps onto them to reward the people who actually did them (we don't know what the rewards will be quite yet). But Boubouille at MMO Champion has a good line on what's up with the scrolls-- they still drop, but now instead of granting attunements, they grant flasks, usable in all the higher level raid instances.
The good news, as we heard at BlizzCon, is that Blizzard says they've learned their lesson from this fiasco, and attunements in upcoming patches and expansions will be a little less intensive (which is fine by me-- I'd rather difficulty keep people away from a dungeon rather than a super-long attunement questline). But if you've got any of these scrolls still around, feel free to use them for flasks. As a commenter says, it's a buy and use 25 flasks, get 5 free sale!