There is a certain segment of the population that finds pre-marketing confusing, and this segment is larger than you would expect. Thus when they see an advertisment for a book, they immediately come to the library and ask for a copy. Now as soon as a book is put on order by the library, we can place a request or "hold" for you on that book. So that when we get the book, you'll already be on the list. This doesn't mean we have the book yet. And thus the confusion begins.
Of course you heard that Sarah Palin's book is coming out. Naturally we're already getting requests; they started the day after the announcement. So the conversation goes something like this:
Confused Patron: I'd like Sarah Palin's book please.
Patient Librarian: That won't be out for six weeks, can I place a request for you?
CP: But they were talking about it on the news.
PL: That is because it was just announced, but it won't be available for another six weeks.
CP: But they were showing it on the news.
PL: The cover art has been released so they can show the cover, but it is not available yet. Can I place a hold for you?
CP: But I saw it in Barnes and Noble!
PL: I believe you saw a poster advertising pre-ordering the book as it won't be available until Nov X. (at this point I'm usually pointing to the bolded release date on the amazon.com screen) Can I place a hold for you on the book for when it does come out?
CP: And how long will that take before I get the book?
And on we go. I have this conversation dozens of time whenever a new hot book is released, or getting ready to be released for either kids or adults. Recently (and by recently I mean for the last four months), I've been having this conversation with children about Diary of a Wimpy Kid: Dog Days by Jeff Kinney, the fourth book in a very popular series which I promise is not going to be released until October 12th. No your friend didn't have it, they had an ad for it in the back of the last book, no you didn't see it in Barnes and Noble, you saw a poster, yes I'm sure, no I'm not trying to keep you from getting the book.
I feel sorry for these people. Do they go to the movie theater and demand to see a movie right now that won't be released for weeks? (But I saw it on TV! But they showed it on Letterman!) It seems like a tough way to go through life if you don't understand pre-marketing.