Now that HP has introduced their Slate 500 tablet PC, it's important to note that it's a PC. It may look a lot like an iPad, but it has a "real computer" operating system (Windows), unlike the iPad which is what I've been referring to on this blog as a "no OS" device. This makes them entirely different types of product, and the comparisons that are popular in the tech press right now (e.g. 9.7-inch screen vs. 8.9) have little point. The iPad is a true consumer electronics device, like a TV set or an iPod is: just turn it on and use it, but don't expect to run applications that need a real computer. The HP Slate is very different: it can handle those applications, but you have to wait for it to start up, you have spend a lot of time learning how to use it, you have to do a lot of work to keep it updated, etc. For an iPad-like "no OS" device from HP we'll have to wait for the PalmPad that will appear in 2011.
As time passes, however, even the "heavy work" that currently requires a "real computer" is becoming available as services delivered over the Internet, e.g. instead of buying and installing Adobe Photoshop on your computer, use Photoshop.com's editing tools from any device that contains a web browser. (And that supports Flash, which rules out the iPad, but to get around this Adobe has created an iPad app for use with Photoshop.com. The PalmPad will support Flash.) Eventually hardly anyone will need a "real" personal computer, since the iPad or PalmPad or something like it (possibly with a larger screen, possibly with a keyboard accessory) will do everything you need. I'm looking forward to not needing a Windows (or Macintosh, or Ubuntu) laptop any more.