With the launch of the Apple iPad — and its iBookstore — just two weeks away, “strong initial pre-orders for the iPad (along with its sexy television advertisement) make it possible that Apple could meet or exceed the number of Kindles in the marketplace in short order,” observes Michael Cader in this report (subscription required) for Publishers Marketplace. And as you can guess, that’s bringing out the best in Amazon.com.

Yep, you guessed it: Amazon is once again issuing threats to remove buy buttons from publishers who don’t play ball. According to Cader:

At least one independent publisher of scale was told categorically by Amazon in a recent phone call initiated by the etailer that Amazon would not negotiate agency selling terms with any other publishers outside of the five initial Apple partners. This publisher was told that if they switched to an agency model for ebooks, Amazon would stop selling their entire list, in print and digital form. In conversation, Amazon is said to have reiterated that as matter of policy they are declining to negotiate an agency model with any publisher outside of the five who have already announced agreements with Apple’s iBookstore.

In a stirring development, however, it seems independent publishers may try to stand against Amazon the way most of the Big Six publishers did:

In other conversations, executives who did not want to speak for attribution indicated an inclination to move forward with Apple and stand firm on any resistance from other customers–along with a hope that they wouldn’t be standing alone in taking such a position. Though publishers traditionally do not discuss such matters with each other out of legal concerns, the publisher receiving the direct threat cited above is exploring with counsel the extent to which they might be able to consult with other independent publishers facing a similar choice.

Of course, Amazon didn’t like the fact that most of big publishing stood up against them, and in a surprising note Cader reports that …

… ongoing negotiations between Amazon and the outstanding Agency Four (Hachette, Harper, Penguin and Simon & Schuster) remain unresolved for now. If you thought the discussion over the resetting of terms was over and done with after Amazon admitted that “ultimately” they would “have to capitulate and accept Macmillan’s terms,” then think again.

At the time, Amazon told customers “Macmillan has a monopoly over their own titles, and we will want to offer them to you even at prices we believe are needlessly high for e-books.” But now, according to those who have been briefed on the negotiations, Amazon continues to use the threat of removing buy buttons from publishers’ physical and digital books.

The indications are that if the Agency Four have not finalized new digital sales agreements with Amazon prior to the launch of Apple’s iPad, they could face delisting from direct sale at Amazon, as Macmillan did.

And as if Apple wasn’t making Amazon feel cornered/crazed enough, there’s also this to consider, says Cader: “Google is on the horizon and continues to take a flexible position in discussing an agency model for the forthcoming Google Editions, publishers say.”