Not it does not cover picture messaging. In the fine print:
Restrictions: Add-on does not auto-renew after 30 days. Includes international text messages while travelling within the U.S. Availability of service to international destinations will vary by country and is subject to change without notice. Excludes MMS messages (picture& video), premium messages and subscription based messages.
I think MMS may be charged on pay per use rates of $0.60/message but I'm not 100% sure