There is a major difference to the GIF debacle. GIF was always implemented in software. OTOH H.264 decoding happens mostly in hardware.
Even on PC's, H.264 is supported in hardware by recent nvidia (purevideo HD) and ati cards (avivo HD)- and I presume intel follow. Lets see if intel will do it on a codec on their GMA graphics chips or with SSE264 extension featuring DECODE264 SIMD instruction will be interesting to see...
Why is that relevant? Because if implemented in hardware, the software doesn't need a patent license. When implemented in hardware, it will be no more relevant than the patented X86 instructions are to users. Sure, they eliminate competition, but it doesn't free software from using them.
I'm afraid mozilla has choosen an fight they can't win. IE, safari and chrome will support H.264, and someone will write a firefox plugin to do it as well. The only thing the fight will create is delay in html5 video adoption - and meanwhile the video still gets distributed in H.264 - in flash container. Which leads to the question:
Is it more important to eliminate flash or H.264? Mozilla has seemingly taken the latter one as more important.
 Which actually might be a DSP executing firmware.