Apple’s review process has seen dramatic improvements in 2009. The review team is more responsive now.
For those who are not familiar with the submission process to ITunes Store, here is a summary of the steps involved:

1) The development team uses a software package called XCode to build a binary of the application with appropriate signature.
2) The application is then compressed and uploaded to Apple’s iTunes Connect site. In addition to the compressed binary, a 512×512 image representing the app on ITunes Store must be uploaded. A scaled-down (57×57) icon of the same image must be used by the application as an icon on the customer iPhone home screen. An Additional five snapshots of the app can be uploaded. These images will be used by users browsing the store to get a feeling of the app.
3) Description of the app (for every localization) is also required in this process.
4) The price and geographic distribution (Only US, Global, etc.) is also required.

After providing this information, the app can be submitted for review.

At the time of this writing, Apple usually respond within a week. I have noticed that they work weekends! Well, at least Saturdays. If you’re lucky, you don’t hear from the review team at all. Instead, you receive a wonderful message saying: “Dear John Doe, The status for the following application has changed to Ready for Sale.”
It takes less than three hours from the receipt of this email for the app to show on the iTunes Store.

If, on the other hand, the review team is not happy with some aspect of your app, you receive a snapshot of the screen having the problem with a reference to a section in the iPhone’s Human Interface Guideline document, such as the following:

“Please review the Handling Common Tasks section of the iPhone’s Human Interface Guideline here:

You fix the problem, and submit a binary again. You do not need to change other aspects of the submission if the problem is in the app itself. If the review team finds another problem, they respond back (within a week) with another snapshot and another section to read.

This process repeats, until you give up, have a heart attack, or you receive “Ready for Sale” email.
Sorry, you don’t receive a list of issues before hand. One issue at a time!

You can change the price of the app, its description, etc., anytime after the app appears in the store. A new binary however, requires that you go through the process again. Once a revision is approved, the old version is removed and is replaced by the new one. This swap is not instantaneous; no sales for about three hours!

Currently, 17,000 apps in 20 categories are available. Unless your app simulates body sounds, good luck getting noticed.