One of the plethora of problems I’ve had with MacPorts after installing Snow Leopard was the following error:

/opt/local/bin/phpize: line 159: 13947 Segmentation fault      $PHP_AUTOCONF

Turned out, this meant that my autoconf was out of date (line 159 of phpize is autoconf). The way to resolve this is with:

$ sudo port upgrade –force autoconf

After this, things seemed to work again.

Hope this helps somebody