I very much doubt that going into 2010, many people had Adobe vs. Apple pegged as the most colorful tech feud of the year. Microsoft vs. Google, sure, or even Apple vs. Google. Oracle vs. Salesforce? Why not. But the escalating war of words between Steve Jobs and Adobe over Flash has proven not only to be intellectually engaging, but also darn entertaining.

Today, Adobe stepped up the fight, as the company's co-founders, Chuck Geschke and John Warcock, posted an open letter that takes aim at Apple's locked-down mobile platform. By blocking Flash and controlling what iPhone and iPad users can see online, Apple "has taken a step that could undermine this next chapter of the Web," they argued.

"If the Web fragments into closed systems, if companies put content and applications behind walls, some indeed may thrive -- but their success will come at the expense of the very creativity and innovation that has made the Internet a revolutionary force," wrote Geschke and Warcock. They finish with a nice flourish: "In the end, we believe the question is really this: Who controls the World Wide Web? And we believe the answer is: nobody -- and everybody, but certainly not a single company."

That was only the first prong in a two-part attack, though. Adobe has also started a new ad campaign: We [Heart] Choice. The ad, which ran in the Washington Post and is up on sites like Ars Technica and Engadget, announces in large text that "We [Heart] Apple" with the Adobe logo underneath. But, it turns out, maybe they don't heart Apple all that much, since that message is followed by a less glowing statement: "What we don't love is anybody taking away your freedom to choose what you create, how you create it, and what you experience on the Web."

The closed vs. open argument has taken on a life of its own in this debate, and neither Adobe nor Apple really fit squarely on either side.

In his own open letter, posted late last month, Jobs pointed out that "Adobe's Flash products are 100 percent proprietary. ... While Adobe's Flash products are widely available, this does not mean they are open, since they are controlled entirely by Adobe and available only from Adobe. By almost any definition, Flash is a closed system."

Jobs pointed to Apple -- despite the proprietary nature of its mobile OS -- as the actual champion of openness, given that it has rejected Flash in favor of HTML 5 and other open standards. "Perhaps Adobe should focus more on creating great HTML5 tools for the future, and less on criticizing Apple for leaving the past behind," he said.

But aside from Jobs' arguments about Flash's reliability and security issues (and its effect on the iPhone and iPad battery life), he had a tough time arguing that Apple isn't restricting what its users can access online by prohibiting Flash.

And that's a point that Adobe is jumping all over. As its co-founders argue, "We believe that consumers should be able to freely access their favorite content and applications, regardless of what computer they have, what browser they like, or what device suits their needs."