The plug-in the linked page discusses is for Shockwave Flash, what most people have just called "Flash" for some time. Macromedia had lost interest in Director--and therefore, Shockwave--even before they were bought by Adobe.

I don't recall a true Shockwave plug-in ever being released for Linux. There have been ways of getting the Shockwave plug-in for Windows Firefox to run in Linux Firefox using Wine, but that's a trick for x86 processors only. Internet Tablets would need to add a layer of processor emulation, which would slow everything down to unusable levels, if it could be coaxed into working at all.

As for the linked page, it's rather dated and explains how to install a beta of the Flash 9 plug-in for x86 Linux on a distribution newer than the Flash installer expected. Time has moved on, and at this point, current tech for x86 Linux is a Flash 10 plug-in, and Adobe has even released a beta Flash 10 plug-in for x86-64 Linux. None of that helps the non-x86 tablets though.