A couple of parts to my answer... 1) apt-cache show <pkgname> has this info, capt will show it in a more concise manner (capt is only in unstable at the moment, though it works fine in frozen too).
2) are you aware that ppc binaries are available from ftp.mozilla.org, and weeklies (or so) from http://southpole.penguinpowered.com/)? They are built on debian by yours truly... if you just need a more recent one, I'll upload a new one to southpole tonight. 3) if you're the kind of person who just likes to build from source (hey, I am) are you intending to build a fully debug-symboled mozilla (which takes ~1 gig btw). if not, use --disable-debug (and probably --enable-optimize if you want it to be fast) and the size requirements should be ~350 megs instead.
