How to use macports Python in a cron job?
The result of the PATH variable is quite different in the cron world. Invoke the script with the full path to the python binary (e.g. /opt/local/bin/python2.7) and you should be good.

This can be examined by running env as cronjob and comparing it to the result of running env as yourself in Terminal:

user's cron env:

PATH=/usr/bin:/bin:/usr/sbin:/sbin
...
SHELL=/bin/bash
HOME=/Users/user
USER=user
PWD=/
...


compared to user's env:

PATH=/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin
...
SHELL=/bin/bash
HOME=/Users/user
USER=user
PWD=/Users/user
...




Alternatively you may add the PATH to the crontab:

sudo nano /var/cron/tabs/user


In newer systems (probably ≥10.6):

sudo nano /private/var/at/tabs/user


Change

...

*       *       *       *       *       some command


to

...
PATH=/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin

*       *       *       *       *       some command