As I wrote in another thread, I believe all the evidence points to some sort of iPad upgrade or price change in the fall coinciding with iPad OS4 release and the holiday season.
Yes Apple is selling hundreds of thousands of iPads. I'm sure that they'd like to sell millions of them. It just makes a lot of sense that they would try to clear out some stock during back to school and then release a refreshed and/or downpriced model for the holiday season.
I'm not talking anything major, but perhaps they simply include the 3G features in the normal price, perhaps they add a front camera (I doubt rear camera), or perhaps they discontinue the 16GB model and drop the price points for the remainders.
I think a good point to think about is how the iPod Touch doesn't have a camera yet. Well I think it will soon. There's no easy way to get the iPod Touch (or iPad) to 128GB of storage space. a 64GB flash memory card costs more than $100 as Apple's wholesale cost. They won't be doing that for a while. So if Apple wants to keep their prices, but can't increase the flash storage, then one thing that they will probably do for the iPod Touch is include a camera. One thing they will probably do for the iPad is include a forward camera.
And "fall" could be 7 months from now. Nobody who buys an iPad now should care. Nobody thinks, "oh I should have waited seven months for the next model". If you like the iPad now at current prices, you shouldn't hesitate to buy. Just don't be pissed when there's a refresh or price drop of some kind in the fall.
A lot of people on the forum hold this misinformation that Apple updates all its hardware exactly once a year. This is false. Maybe it updates the physical hardware that often, but it also has hardware-unrelated pricedrops and if you look at the MacRumors Buyer's Guide you see that most things are either updated or pricedropped every 200 to 250 days.