Posted by: F8sHanD
This is a limitation of Firefox 2. The font rendering technology cannot deal with the font, and so it ignores the font (Microsoft Office does the same thing). Firefox 2 will almost assuredly never support fonts like SBL Hebrew. Firefox 3, of which there is a publicly available beta, does support the font, and it will display the page you linked in SBL Hebrew.
Like Safari, however, even Firefox 3 does not position the vowels and diacritics correctly. This has to do with the technologies that OS X uses to render text. The older technology, ATSUI, does not provide support for complex layouts of OpenType fonts like SBL Hebrew, so one is left with the garbled mess that you now see. There is however, a newer technology called Core Text that does the layouts correctly. You can see the advantages of this API, which does support OpenType layout tables, in TextEdit. If you paste (or type) Hebrew text with SBL Hebrew in it, the layout is generally correct. The major drawback of Core Text is that it is very new and only available in Leopard. As such, it will be quite some time before it is widely implemented. There is some discussion about implementing it in Firefox here , but I would guess it will be a while.
Hope that is helpful.