In this month’s FREE php|architect issue (available only in PDF), Eric David Benari provides a list of much more specific things to check on the implementation side. It almost sounds like “did you brush your teeth before going to bed?” (I say this in a good way), with things such as having your 404 and 403 pages set up properly, ensuring browser-side caching is specified correctly, serving data and files from RAM not from disk as much as possible, and more. It’s a useful list with good sample code, I recommend it to new web developers as an overview of what aspects of coding for performance deserve attention, and to more experienced coders as a handy cheat sheet.

Now for a bit of a critique. Some of these coding techniques will help a site’s quality a lot, but frankly, if you are testing, then you’ll find out about these issues earlier than at the time of going through the checklist. 

Others will increase your site’s performance by a lot, but if you are benchmarking your app to meet a specific demand, then you’ll know there is a problem (or not) before you look at the checklist.

What really matters is that (a) the way you’ve coded your app and deployed it, it will provide the expected quality of service, and (b) when you need to improve performance, you have a solid idea of how to do so (improve the code, re-code, add hardware resources.) The techniques outlined in Eric’s article are key to both.

So I’m going to stay with my more abstract checklists, along which I have very concrete toolboxes such as the “coding checklist” in Eric’s php|architect article.

Here is a summary of the distinctions, taken straight from Apple’s iPhone developer’s web content.

Web Application on Safari Mobile version 4:

You cannot arbitrarily access the iPhone’s resources (the camera, GPS, audio, files, data, applications, etc.)

But:

You can make it look and feel like a native app:

How do I ensure that my web content uses all of the available screen space on iPhone?
How do I create a Home screen icon for my website or web application?
How do I hide the Safari on iPhone OS UI components when my web application is running?
How do I disable user zooming and scaling in my web application?
How do I detect iPhone orientation changes in my web application?
How do I conditionally load CSS that I have customized for iPhone?
How do I launch iPhone applications, like YouTube, iTunes, or Maps, to display content?
How do I dial a phone number from a webpage on iPhone?

(read the answers at Safari on iPhone User Experience Coding How-To’s)

You can make it view/play/perform content in native iPhone apps, a bit like a desktop browser plugin would, using Apple Url Scheme:

“Mail Links” describes the format for sending email with the Mail application.
“Phone Links” describes the format for dialing phone numbers in the Phone application.
“Text Links” describes the format for launching the Text application.
“Map Links” describes the format for specifying locations in the Maps application.
“YouTube Links” describes the format for linking to YouTube videos.
“iTunes Links” describes the format for linking to items in the iTunes Music Store.

(quoted from Apple URL Scheme Reference)

You can make it work offline:

… Safari provides an offline application cache. This cache allows you to create web-based applications that work correctly even when the user’s computer or web-enabled device is not connected to the Internet.
(quoted from HTML 5 Offline Application Cache)

… Safari supports the HTML 5 client-side storage specification.
(quoted from Key-Value Storage)

… Safari supports the HTML5 JavaScript database class. The JavaScript database class, based on SQLite, provides a very basic relational database intended for local storage of content that is too large to conveniently store in cookies (or is too important to accidentally delete when the user clears out his or her cookies).
(quoted from Using the JavaScript Database)

(get the complete PDF document at: Safari Client-Side Storage and Offline Applications Programming Guide)

Native iPhone application:

Unlike a web application, which runs in Safari, a native application runs directly as a standalone executable on an iPhone OS–based device. Native applications have access to all the features that make the iPhone interesting, such as the accelerometers, location service, and Multi-Touch interface. They can also save data to the local file system and even communicate with other installed applications through custom URL schemes.

(quoted from iPhone Reference Library)

Ulitzer.com has a some stats for an informal poll on LinkedIn about which (web or native) developers seem to favor:

Web or SDK?
— Web Development and SDK Development each offer distinct advantages to the iPhone Developer…So I set out over the last two months, with the aid of the LinkedIn Polls feature to gauge the trend

And btw they also have a simple summary of what you need to do to get your first iPhone application out there, starting from 0:

Seven Steps to the iPhone Developer’s World
… here are my seven steps to becoming an iPhone Developer. Tread carefully and you will become a wise man… Buy an Intel Based Mac & a Device – though the iPhone/iPod Touch device isn’t 100% necessary for this early stage, as the iPhone simulator that you will get with the SDK is free and more that capable for initial development …

I hope this helps clarify your options as a developer for the iPhone.