As a big fan of tweetie for iPhone and mac I've had some knowledge of instapaper as a service for some time. It had a mobiliser function that tweetie has been able to tap into. Essentially it reads a web link and strips out the non content material. The navigation, advertising etc and displays the page in a mobile/iPhone readable and optimised format.
On sunday faced with a slow Internet connection as I am out of town I decided to give the iPhone app a whirl tomsee what it had to provide. 20 minutes later it was on page 1 of my phones app page.
Adding material to it is as simple as hitting read later in tweetie, great for going through my Twitter feed quickly whilse still reading the whole articles at a later time. Also added the bookmarklet to safari on the phone which isn't quite as convienient as it first requires you to load the whole page but is still highly functional.
Third option is to add RSS feeds to it. I have often read brentheber.com as a source for pro tools tips and tricks. Brent has moved on from avid / Digidesign bt I'm hoping he'll continue his great blog posts. Adding his website to instapaper as a folder pulled in his most recent articles all nicely formatted for quick and easy mobile reading.
The iPhone app is great too. My two favourite features are the dark mode which is great for night or dark room reading and the tilt scrolling. The amazing aspect of that is that it takes into account the position of the phone when it is initialised so if I am lying on my back and turn it on tilting the phone backwards slightly causes the upward scrolling to commence. Just superb.