I don't have an iphone, so haven't checked out the app store yet. But i assume Apple has built some iPhone review stuff into the store, seeing as they went to all the trouble of building the 'most popular app', 'most popular free app', etc.

I think you are building for a very small niche market and would have difficulty gaining significant advertising dollars and page views. I should have mentioned in the previous post that my understanding is that without a 20k+ views per day it is VERY difficult to get sponsors on your site.

The 'iPhone app review' portion could be a part of a larger service offering 'all things iPhone' (though I suspect this already exists too) - sell cases/protectors, bluetooth headsets, etc. via Amazon and get affiliate commissions, maybe there are other revenue streams for you as well. My gut instinct tells me that you are in large company and will be fighting for a miniscule portion of a moderate pie.

But don't trust my gut, do your research, you may be on to something, or your research may lead you to even bigger fish.

Your thoughts on 'back-up market of companies who wish to advertise to affluent consumers' misses the targeted point of the value of the CPM is based on the ability to offer advertisers more than just a place to put an ad in front of affluent potential customers.
I believe that if the advertising is off-target, your CPMs would be significantly lower.

Also, i doubt the app store will have the long-term success it has seen in the short term. When was the last time the average (non-geek) friend of yours bought an app for there computer? When was the last time YOU did? Look at Facebook apps. All the rage when facebook launched, then everybody got sick of them. Maybe do a comparison of how many facebook apps are launching now vs. a year ago. That should be a good indication of where the App store is going (in my opinion).
There is very little that needs to be done natively on the device these days. We'll likely have a hybrid of web/native but I hope a few plugins will provide all the native code necessary to run most apps (I'm thinking about writting a plugin myself).

But lets do a bit of research anyway to get you moving further along. I google searched for iPhone apps and got a bunch of sites doing reviews - then put apprater.com & appsafari.com into compete.com to get a monthly page views estimate. AppSafari shows about 57k visits/month and apprater shows almost 18k/month. So reviewing the more successful site - that 57 views for 4.5 pages per user - about 8.5k page views per day X $7CPM = $60 per day.

HOWEVER, I'd say that is a VERY high estimate. Maybe you can do a MUCH better job than appsafari, but they are already in the market and have a surprisingly high number of eyeballs for what there site offers (personal opinion).
You are also competing with sites such as CNET, etc which have iPhone app directories.

Having said all that. I've launched my start-up "HearWhere.com" into a market where there is already an incumbent, and more joining on a regular basis (even a YC supported competitor). I have a competitive advantage and felt the competitors offerings were weak. I'm hoping to launch a new version of the site into Beta late next week which will put even more distance between myself and competitors.

What I'm saying is that if you feel you have a true competitive advantage or opportunity to differentiate yourself in this space, then go for it.
If you're not sure about separating yourself from the bunch, than you probably have more work to do.

An idea I read today through YC relating to Google (I can't remember exactly which article I read) - basically said don't go after revenue, serve the market first, then go for the revenue.

I like that you are planning ahead to make sure the revenue will be there, but I think that may be a bit premature unless you know that the market exists first. Don't just assume that because appsafari has 60k visits, that you'll get the same. Getting people to switch is going to be the biggest challenge for you, and appsafari isn't even the biggest fish to fry - CNET, Wired, etc I suspect are all in this space as well as it already feeds into there user base.

Hopefully somebody more experienced than myself will be able to give you further help and direction with this, and even refute what I've said.