Yup, it is now available from the Mozilla server. Mozilla version 1.4a to be exact. This one is a Nightly Build.

Read More. Created most weekdays from the previous day's work, these will probably work, but maybe not. Use them to verify whether a bug you're tracking has been fixed.
MacOS X, i386 Linux, Windows, Linux PPC, Solaris (2.7/SPARC, 2.6/SPARC, 2.6/x86), Irix, BeOS, HPUX, OS/2, BSD/OS, etc.

Source: Win OS Central