You may not use any of the extra applications on your cell phone, but for some of us, they are very useful. I use Opera Mini on my Cell Phone regularly. As well as Google Maps, and some of the games
. I also use both stanza and eReader for for reading ebooks on my iPod Touch. I am reading my third book in 2 weeks. Its not perfect, but if I was to get a device with roughly twice the screen real-estate as the current one (i.e. a 5" screen), I think it would be just about perfect.
I agree that not everyone of the people who download the app is going to use it, just as not everyone who buys a kindle or a PRS-505/700 is going to use it (at least not regularly). Granted the regular app users are probably fewer simply because the cost of entry is so low, but still, I imagine a lot of the Stanza and eReader downloaders are in fact like me and are actually using them to read. Keep in mind, that eReader is an even better way to track the trends simply because fictionwise also sells books for the reader. They can tell how many people are downloading books they paid for onto the reader. If someone is downloading (over time) multiple books that they paid for, it can be reasonably inferred that they are actually reading said books. Currently, I think there have been something like 300,000 books downloaded from fictionwise to the iPod/iPhone eReader... I am not sure how many of those have been free books versus paid for books, but still...