Almost since the introduction of the iPhone, there have been complaints that it doesn’t support Flash. Those complaints have picked up steam in the last week week, as Adobe demonstrated polished versions of Flash on other mobile platforms—including Android—and all but publicly begged to be allowed onto the iPhone.

Flash, an Adobe product, is software that enables rich web content. It allows developers to add animation, integrate videos, and make websites interactive. A large portion of the web’s content (including advertisements) can only be properly viewed with Flash. On PCs, Flash is integrated into the browser, so users may never realize that they’re encountering Flash-supported content. On the iPhone, however, users will immediately know when a website requires Flash, because the website won’t work. Most importantly, Flash is also a run-everywhere platform—developers can code applications (like games) in Flash, and a user can access those applications via the web.

Thus far, Apple has been hostile to the idea of supporting Flash on the iPhone, to the dismay of Hulu-lovers everywhere. The iPhone’s TOS specify that an application “may not itself install or launch other executable code by any means,” including via plug-in architecture. Steve Jobs has also said that Flash for Macs is too clunky, and that Flash Lite (the prior version used on mobile platforms) wasn’t powerful enough for the iPhone.

Jobs’ argument is less convincing now, though, since Adobe demonstrated fully-functional versions of a new and improved Flash on the mobile platforms Android and Windows Mobile last week. Moreover, Adobe says they’ve got a version of Flash working on the iPhone emulator. But even if Apple and Adobe could work out a perfectly smooth version of Flash for the iPhone—and even if they could take care of some technical hassles, like keeping Flash from draining battery power or memory—Apple would probably still resist Flash. Why? Two reasons.

First, as noted, it’s a development platform. So if the iPhone supported Flash, anyone who had an app rejected by Apple—or who didn’t want to go through the annoyance of being certified and approved in the first place—could code the app in Flash, put it on a website, and let iPhone users flock to it. (The CEO of Nullriver, whose app NetShare was banned months ago, has already expressed interest in this.) According to one survey, 33% of mobile phone users use the phones primarily for entertainment. If all those users had access to free Flash games, the App Store would suffer proprtionately.

An even bigger issue would be the collaboration required to produce a top-quality version of Flash for the iPhone. Adobe could develop a standalone plug-in that a user could invoke to see specific content on the web. But users have gotten used to the seamless integration of Flash on PCs. What Adobe really wants—and it’s saying so quite openly—is to work directly with Apple to integrate Flash into Safari, the web browser offered on the iPhone. This would deeply break down the walls between the iPhone’s native software and the outside apps.

It’s entirely unsurprising that Apple is hesitant to take such a dramatic step. On the other hand, if users choose Android and WiMo phones—so that they have access to the whole web—Apple might have to reconsider its choice. This may be a chance to see market forces resist a tethered device.

—Elisabeth Oppenheimer