Mozilla released Firefox 29. Ubuntu built Firefox packages in the last week. Unfortunately the compiling of Firefox for PowerPC doesn't work at the moment.
Firefox 29 build status for the A-EON Live Remix distribution/Lubuntu 12.04.4: launchpad.net
Firefox 29 build status for Lubuntu 14.04 LTS: launchpad.net
Package build log for the A-EON Live Remix distribution/Lubuntu 12.04.4: launchpad.net
Package build log for Lubuntu 14.04 LTS: launchpad.net
Cameron Kaiser has built TenFourFox 29 (Firefox 29 for Mac OS X PowerPC) successfully: oh-you-big-lug-have-some-australis-you and tenfourfox-29-its-almost-here.html.
Quotes by Cameron about Firefox bugs on Linux PPC:
Unfortunately, the same can't be said for Firefox 29 on other big-endian platforms; bug 961488 is still plaguing Firefox on 32-bit Linux/PPC and the various BSDs, as well as 32-bit SPARC. I'm trying to assist them in the bug, but as you can see, it's not reproducible on OS X and I don't have a Linux setup to build and test on. Hopefully they can pull it together or there won't be a Firefox 29 on your favourite alternative operating system.
Sadly, Linux/PPC isn't likely to fix these first because they're still out of commission due to bug 961488, and the Moz2D code is changing so dramatically that I'm just going to start over with a 31 aurora and try to fix that rather than fix something (29) that's just going to change again. Since 24 doesn't end support until 31.2, I have 31a, 31b, 31.0 and 31.1 to get it right.
Bug report 961488: bugzilla.mozilla.org
Sorry about the bad news of Firefox 29 on PowerPC Linux.