I don't want to be nitpick but what is with the 64bit browser insanity on OS X? No plugins work, OS X is perfectly capable of running 32bit software and by default, except macbook pro and Xserve, iMac, it already opts in for 32bit kernel which is also perfectly capable for running 64bit apps.
Omni group provides a great browser, for free to 10.4.11 users who otherwise would be otherwise abandoned soon (signals are coming) and just because a 1% minority of elitist users want a pure 64bit browser on a OS which doesn't need such backwards things (unlike Linux), 10.4.x will be dropped.
Please tell what would you do if you spotted Omniweb use MORE THAN 4GB of memory? Would you mail support or directly call them? That is what 64bit support is for besides a jokingly 10-12% speed increase which has no guarantees.
Do we really need to reproduce Linux on OS X?
I wouldn't bother if it was Omniweb 6 and Omni group did World's first actual SMP capable browser, using Grand Central etc. but, if it goes 10.5/10.6 just because some people can't live without seeing everything as 64bit on their activity monitor, it is not justice really...
The link to 'IE' under Windows 7 64bit defaults to 32bit version of IE since IE 64bit is incapable of running 32bit plugins (read: FLASH) and talk to any developer about it, including Opera, Mozilla, 64bit browser for today is just elitism and nothing else especially on non Linux operating systems.