By Josh Ong

Published: 02:00 AM EST (11:00 PM PST)

Users are reporting that Apple's MacBook Air models, which were unveiled Wednesday, are shipping without the Adobe Flash plugin installed.

The lack is a departure from previous Mac products, which came with Adobe Flash preloaded, although it remains unclear whether all future Mac computers will ship without the software. Engadget noticed the missing plugin, reporting that Flash content worked fine after Flash Player was installed on Apple's new ultra-thin notebook.

Apple announced the new 11.6-inch MacBook Air models and an updated 13.3-inch MacBook Air version with instant-on capabilities at its "Back to the Mac" event Wednesday. AppleInsider broke news of the 11.6-inch model well in advance of Wednesday's announcement.

Apple and Adobe have been at odds lately, with the two companies' CEOs exchanging barbs in a public war of words earlier this year. This spring, responding to criticism of Apple's choice not to support Flash on its iOS devices, Apple Chief Executive Steve Jobs spoke out.

"Flash has not performed well on mobile devices," wrote Jobs in an open letter in April, noting that Adobe at that time had yet to ship Flash on a smartphone. "We have routinely asked Adobe to show us Flash performing well on a mobile device, any mobile device, for a few years now. We have never seen it."

Continuing to defend the lack of Flash support on the iPad and iPhone, Jobs claimed that Flash is the No. 1 cause of crashes on the Mac. Adobe CEO Shantanu Narayen quickly denied the claim, pushing the blame onto Apple's operating system, calling Jobs' comments a "smokescreen." Narayen told the Wall Street Journal Jobs' accusation that Flash drains the battery life of mobile devices was "patently false."

In May, Adobe responded to Jobs' open letter with an open letter of its own and an advertising campaign. "We [Heart] Apple," the ads read. "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."

Despite the tense words on both sides, Apple decided to 'play nice' last month when it relaxed restrictions on third-party development tools. Adobe had developed a cross-compiler to convert Flash apps into iOS apps, but decided to stop work on it after the tool was blocked when Apple banned intermediary tools in its iPhone 4 SDK license.

After Apple lifted its restrictions of third-party development tools in early September, Adobe revealed that it would continue development of its Packager cross-compiler for iPhone.