Apple took 50,000 pre-orders for their new iPad tablet computer today. They also revealed several new details. First, the mute/vibrate button borrowed from the iPhone will serve a different purpose on the iPad: it will lock the screen orientation. As one of the main uses of the iPad will be reading, users laying on their sides need not be inconvenienced by the built-in accelerometer switching the orientation from portrait to landscape as they shuffle around.

The iPad will also feature several accessibility options, borrowed from Mac OS X. Users can zoom into any area of the screen up to 5X, reverse the display for greater readability, or have books and other text read to them aloud. Apple also revealed screenshots of a la carte 3G ordering, along with alerts that warn the user when they are approaching the lower plan’s 250MB cap.

Apple’s new product is shaping up to be more more than a “big iPod touch.” It’s eReader app, iBooks, looks like a winner. Plus, with full-sized apps like Keynote, Page, and Numbers (think Powerpoint, Indesign, and Excel) already available, the iPad could truly replace the laptop for many more users than people expect.

I want to go on record about the name of Apple’s new tablet computer, which will reportedly be introduced on January 26. Rumors have said it will be called the iSlate, or iGuide, but I still think the name that makes the most sense is iBook.

Consider: Apple owns the rights to the name and has not used it almost 4 years. Tell me a name that fits into Apple’s offerings and makes more sense for a small, book-sized tablet that will act, in part, as an eBook reader? I don’t think the fact that Apple’s former low-end notebook line shared the name will stop Steve Jobs from going back to the well.

The only reason I think Apple may not choose to call their new tablet the iBook is if they want to further highlight the fact that this is not just an eBook reader, but a multi-function computing device. The thing is, everyone knows that, just like they know a MacBook is a laptop. I guess we’ll see in two weeks.