And so I guess you write down on a piece of paper the page number you're in?
As for myself have just an iPhone and a Kobo Touch, but now I have the Kobo I do not read on the iPhone anymore, screen too small ^^
Last time I have to find back where I was in my reading, I just remembered the chapter and a word and I did a search on my Kobo and I found the page I was at this way.
This also means you have to sync your library on all those devices, to be sure to have the book with you when you need so, right?
Perhaps a way to choose the display we want could be helpful then, so people who prefer to know where they are in the chapter can, and when you need an absolute page number you can. Currently the only way I have to know how many pages I need to finish the chapter (useful when I'm going to bed, usually I would like to know if I'm far from chapter end or not) is to go to the chapter list, go to next chapter, look at page number, then come back where I was. Not very convenient.