Portable PDF reader

More and more books, especially tech books, are only available as PDF. Another advantage is I can get the PDF delivered immediately rather than the "2-4 weeks" amazon.jp likes to tell me. But I don't like sitting at my computer to read - I want to be able to sit in an armchair, on the train, in a cafe, etc. to read (see also my moan about php Architect magazine going PDF only)

I've done some searching, and some asking, and I suspect the device I want does not yet exist, but I'm open to suggestions. I don't want the heavy bulk of a notebook. The Kindle (or similar) seem hard-wired for content being sold by Amazon (or whoever), which is no good at all (Update: PDF supported since version 2.3, and content can be uploaded over USB cable; see wikipedia article)

I'm very interested in how easy it is to read a PDF formatted for A4 on an iPhone (or iPod Touch), as that would have lots of other advantages (e.g. portable video player, as well as portable email and web browsing in the case of the iPhone).

UPDATE: list of e-book readers
Apparently the Consumer Electronics Show in Las Vegas this month will see some new e-book readers announced. So, sitting on my hands seems best at the moment.

UPDATE:
Video demo of AjiReader viewing a PDF on the iphone (apparently the app costs $1)

Another video demo showing PDF, DOC, XLS, PPT but the comments seem to be saying you need a jail-broken phone for this?

UPDATE: (8 months later!)
The new Kindle looks good. I decided to stop Waiting For The Next Big Thing, and went ahead and pre-ordered one. It does PDFs, it does Japanese, everyone I've spoken to says e-ink is great; but, above all, at $139 it is now affordable.

I also ordered the case with built-in light; it was 1/3rd of the total cost, so I dithered a lot about that. But while I think the case is over-priced it also looks very cool.

Some people said the 6" screen is still too small to read A4 PDFs in comfort. If I find it unusable for that (my key need) I'm hoping I might be able to resell it at only a small loss. After all, ordering from Japan is a pain.

I'll put up a review in about a month. Watch This Space :-)