The Apple Blog engages in a bit of wishful thinking:
Microsoft had their chance at defining a market. They pushed for the
creation of the Ultramobile PCs (“UMPCs”). The Windows-based
mini-tablets have not found their market. However, the Apple iPhone
(and now the iPod touch) is actually the UMPC done right.
Um. Not quite. The iPhone isn't big enough to be a UMPC, and doesn't include USB ports so you can use a mouse and keyboard. It doesn't work with Mac OS X software and indeed can't be extended in any way. Heck, the iPhone doesn't even support Cut and Paste. Think about that for a second.
What the iPhone really is, is a new computing platform. It sits at the Windows Mobile level, not the UMPC level. It's a smart phone for consumers, or an entertainment device. But it is most definitely not a UMPC, sorry.