used this to build php extension on g5 running os x 10.5 (leopard) which worked with marc liyange's universal binary php5
(english only, change enable/disable for other languages)
http://pecl.php.net/package/stem/ (stemming, based on snowball)

sudo /usr/local/php5/bin/phpize

CFLAGS="-arch ppc -arch ppc64 -arch i386 -arch x86_64 -g -Os -pipe -no-cpp-precomp" CCFLAGS="-arch ppc -arch ppc64 -arch i386 -arch x86_64 -g -Os -pipe" CXXFLAGS="-arch ppc -arch ppc64 -arch i386 -arch x86_64 -g -Os -pipe" LDFLAGS="-arch ppc -arch ppc64 -arch i386 -arch x86_64 -bind_at_load" ./configure --target=ppc64 --disable-stem-danish --disable-stem-dutch --enable-stem-english --disable-stem-french --disable-stem-finnish --disable-stem-german --disable-stem-hungarian --disable-stem-italian --disable-stem-norwegian --disable-stem-portuguese --disable-stem-romanian --disable-stem-russian --disable-stem-russian-unicode --disable-stem-spanish --disable-stem-swedish --disable-stem-turkish-unicode --with-php-config=/usr/local/php5/bin/php-config

make
sudo make install


-- harvey.nu computer stuff