There are a couple of client libraries for the PopIt API which should make integrating PopIt into your project easier.
Available at https://github.com/mysociety/popit-python.
Available at https://github.com/opennorth/popit-ruby.
Available at https://github.com/mysociety/popit-php.
Available at https://github.com/mysociety/popit-django.
If you’ve got a library that speaks to PopIt that isn’t listed here or you’d like to write one then get in touch on the Poplus mailing list.