When Apple (Nasdaq: AAPL) introduced the iPad in January 2010, it made a controversial decision not to support Adobe Systems' (Nasdaq: ADBE) Flash software. At the time, Adobe said Flash supported almost 75% of Web videos -- including YouTube -- and 70% of online gaming sites.

It was a gutsy move for Apple. As an alternative, Apple looked to a new technology, HTML5, to display Internet videos and graphics on its iPad, iPhone, and iPod Touch.  Only about 10% of Web videos could be played with HTML5 when the iPad was first announced.  Apple explained its decision by criticizing Flash's speed, battery consumption -- an especially important feature for mobile devices -- and vulnerability to malware such as viruses.

Flash Android to the rescue?
Flash was an obvious potential differentiator for wannabe competitors to the iPad. That wasn't lost on Google (Nasdaq: GOOG), which promotes its free Android operating system to smartphone makers. Android runs Flash. It also runs on tablets, with Google recently releasing an optimized version named Honeycomb.

The Samsung Galaxy Tab, an early iPad competitor, runs Android … and, therefore, Flash. Motorola Mobility's (NYSE: MMI) much-anticipated Xoom tablet, which became available in late February and runs Google's new Honeycomb update, runs Android and is Flash "compatible." That said, Xoom won't run Flash until its software is updated this spring.

Flash isn't limited to Android tablets. Research In Motion's (Nasdaq: RIMM) PlayBook tablet, rumored to be available for purchase in late March or early April, will run Flash. So will Hewlett-Packard's (NYSE: HPQ) webOS tablet, which is scheduled to be available "in the summer." 

Outvoted, but not outmaneuvered
With tablet competition heating up and major competitors lining up behind Flash, it seems Apple was outvoted. But it wasn't outmaneuvered. By February of this year, about 63% of Web videos could be played using HTML5. That compares with 10% in January 2010. Apparently, websites see power in the Apple platform.

Even Adobe seems to be making concessions. Recently, the company released a new tool that converts Flash files to HTML5 so they can run across Apple mobile devices.

Foolish takeaway
The tablet wars are just heating up, with the second-generation iPad launching as many competitors are introducing their first-generation tablets. The rapid adoption of HTML5 suggests that one feature many tablet makers hoped would help them compete -- the ability to play Flash -- isn't going to be a differentiator. Gentlemen, start your tablets!

Looking to keep tabs on the major players in the tablet wars? Add any of the above companies to our free watchlist service, My Watchlist.

If you know an iPad in need of a loving home, please contact Fool contributor Cindy Johnson. First generation is fine. She currently owns no shares in any of the companies in this story.

Google is a recommendation of Motley Fool Inside Value and Motley Fool Rule Breakers. Apple and Adobe Systems are Motley Fool Stock Advisor recommendations. The Fool has written puts on Apple. Motley Fool Options has recommended a bull call spread position on Apple and a diagonal call position on Adobe Systems. The Fool owns shares of Apple and Google. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.