No past version was a target guarantee to have Win64 for Release but more of a possibility or speculation as there have been Win64 builds on the Beta channel since 37.0b2 build.

I take it you mean the Win64 (64-bit for Windows) and not about Mac OSX and Linux builds which has had 64-bit Release builds since Firefox 4.0 both because easier to do and needed.

If all goes well the Firefox 41.0 will be the first Release to have Win64 builds alongside the 32-bit Windows builds.

No Firefox version was targeted for Win64 Release. Then on short notice for a brief time a few weeks before Fx 40.0 Release Mozilla thought about making Win64 for Fx 40.0 Release but was changed to Fx 41.0.

Two things of note for Win64 Firefox builds starting 41.0+ Release. Only the 64-bit Flash Player is white listed to run in Win64 Firefox. Seconed one needs 64-bit Windows 7, 8.x and 10 as the 64-bit Windows XP, Vista and servers cannot run Win64 builds ever since Firefox 37.0+ development builds.

Ah, forgot to specify Windows. Thanks for the quick response.

An update: The Win64 for Firefox 41.0 Release may not happen after all.

https://bugzilla.mozilla.org/show_bug.cgi?id=1185532#c14 for reading as the Bugzilla is not a discussion forum and Why? comments are spam.

Your link didn't work.

Edit: Nevermind, the site was just down for a bit.