There is a story revolving around the blogosphere that Iran has rush ordered armored water cannon vehicles from China, and that they may be headed to Tehran. In reality, a number of Iran's municipalities already possess them. They've been seen at previous year's military parades, including those held in Tehran. Below are photos of such vehicles taken well before the June election. So far, there's no evidence they've been activated for use in riot/crowd dispersal operations post-June 2009 election. These types of vehicles do offer a less-lethal form of riot control and have been used extensively in the West, including Switzerland, Germany, France and even Seattle, USA.
This is an Islamic Republic of Iran Police Force (IRIPF, or NAJA) armored water cannon vehicle on display in Isfahan. Visible is the large front-mounted, angled blade.
Another view of the IRIPF vehicle in the background. Visible are the top mounted (unmanned) dual water cannon stations.