This book is a reward from this quest: http://classicdb.ch/?quest=5128. You will get it in your mailbox after a day or so. I suggest you read it, if you're even a bit interested in background and lore. I like how Blizzard takes the time and effort to actually add some background to certain enemies (like the Winterfall in this case).
Not everything in the game has to be tied to a quest, or have a reward.  When I finished the quest and the NPC says, "when I've figured out more I'll let you know," I was kinda disappointed, but enh, whatever.
I was plesantly surprised to login the next day and find that mail.  :-)
As for the firewater, it's just a random drop.  No items or quests required to get it.
There are other quests which involve the mail as well.  When you finish the Cauldron quests as Horde, for example, High Executor Derrington(sp?) sends you a note thanking you for your help, and inviting you to "stop by and go on a cauldron run sometime" with him.  It's pretty funny.
the npc mailed this back to me after translating it.. but what do I do with it? it talks about firewater, so it seems like it should be a quest pointer...
That quest is where you get the book from.  You finish that one, and the guy mails you this book in a few hours.  Weird, never did a quest where you got your reward thru the mail.
Anyways, this thing just appears to be a waste of pack space.  I'm gonna unload it.  If I find any reason to regret that choice, I'll post back here.  Otherwise, I'd recommend dumping the thing.
there's no point in the book except for the story line history then? i was going to go back to the druid to check it out, but someone said it didn't help. i think i agree with the 'say no to drugs' program. or possibly the 'keep us playing' program. thanks for the info guys. i just got the book today, and m already going insane lol. i think il bank it. it might come in handy at some point in the Burning Crusade...
Hmmm. have read everything posted so far and it does appear to be junk. The text of the mail you receive that encloses the book from Kelek Skykeeper does give the impression that there is more to come though. The mail finishes with " If you are ever in need please visit me again"
Storywise, this does somewhat connect with the final Timbermaw quest, the one to get the epic trinket, where you ahve to kill the demon corrupting the Winterfall.
We just received this quest 02/05/2007 and there is still no indication you can do anything with it.
On the off chance it might be linked to either a class or profession we tried with a Priest/Alchemist and Hunter/Leatherworker/Enchanter and still...does nothing.
We also ran over to Donna in WS to see if anything else could be done with no luck.
SO...IMHO...trash the book and save the inventory space!
If you read the quest carefully it mentions the Emerald Circle. So, I went to the Emerald Sanctuary and found Kelek Skykeeper. Nothing happened. Got 6400 experience. How boring.