For those unaware, the pricing v. price-drop dates graph has the Kindle on a straight-line path to $0 by November 2011. Word is when Amazon CEO was asked about that, he responded "ah, someone noticed" and changed the subject. How, when & whether this will happen is interesting.
My main reading use case is in bed at night. I have a little booklight for reading actual paper books, but I think I'm waiting for an AMOLED 8" tablet for e-book reading. It works pretty darn well for my phone in low light conditions. (In fact the main competition for an 8" tablet would be one of those giant 5" phones with AMOLED).
People seem to get a bit religious about pentile. It doesn't make any sense to dismiss (or accept) it without considering all the other parameters. It's designed to make it easier and cheaper to hit certain resolutions and densities. If I could get more pixels or density for the same money then I'd happily take pentile. If there's not much extra gain over not using it, or not much extra cost, then I'd happily leave it out. It also, for whatever technical reason, seems mostly to be associated with OLED technologies, though OLED does not necessarily imply pentile. I think Samsung brands their non-pentile AMOLEDs as SAMOLED plus and they have them either on the market or due very soon in both big phone, massive phone and mid-size tablet varieties.
However, OLED does have the one advantage I mentioned about reading in the dark which decides this for me. For that reason alone I personally am waiting for a sufficiently high-density AMOLED tablet for reading purposes. Pentile will be just one factor in weighing up my options, certainly not a deal breaker.