The U.S. Apple Online Store is now shipping all iPad 2 models in three to four weeks. After an initial estimated shipping time of three to five days, the Apple Online Store is clearly struggling to meet demand. As a result of this, latecomers are going to have to wait before their iPad 2 is delivered to them.

Both the Wi-Fi only and Wi-Fi + 3G models have the same estimated shipping time. If you’re desperate for an iPad 2, you could always try an Apple Retail Store, though many people haven’t been having much luck there either. Alternatively, you could visit your local AT&T store, Verizon store, Best Buy, or Walmart – though I think it’s fair to say that, at the moment, the second generation iPad is in high demand, and getting one will probably be tough.

Currently, the iPad 2 is expected to launch internationally on March 25 – meaning, if you can afford the plane ticket, it may make more sense to visit Europe and pick up an iPad 2 there.

You can check out the iPad 2 in the U.S. Apple Online Store by clicking this link. And, if you managed to get a second generation iPad, let us know in the comments.