Last fall, activists opposing the Supreme Court nomination of John Roberts recruited 25,000 volunteers for their Massive Immediate Response effort. Each volunteer agreed to respond immediately to a text message requesting that they call their Congressional Representatives. The 27% opt-in rate was five times that observed for the most successful commercial entertainment campaigns.

Rick Santorum, the Republican incumbent running for U.S. Senate in Pennsylvania, used SMS to reach out to his supporters.

On Halloween, Pat LaMarche, the Green Party candidate for Governor in Maine, asked her supporters to provide topic suggestions via text message for a speech at an upstate university.

Note that all of these initiatives relied upon participants who were already fired up for or against particular candidates and issues — SMS is less likely to be useful in converting a luke warm supporter into a passionate participant.

Almost one third of all cellphone subscribers send at least one text message per month, with younger Americans leading the way. A recent New Politics Institute study notes that cellphone subscribers comprise more than two-thirds of the population, that more than half of 18 to 34 year olds use text messages at least occasionally, as do one in five 35-54 year olds.

Among those 35 and under, text messaging reverses the digital divide. Five out of ten Hispanics, four out of ten African Americans, but only three of ten whites use their cellphone text messaging capability. So it should not be surprising that Voto Latino announced plans in July to register at least 35,000 Hispanic youths nationwide using cellphone text messaging tools.

These tools are rapidly reaching the “point and click” stage for campaign organizers. For instance, the Mozes service allows campaign manager to set up “text message ballots” easily. A “do it yourself” American Idol is using this service to let listeners to indicate the band they prefer in one on one matchups.

To track developments further, visit mopocket, textually, and the MobileActive Community Blog.

Update: 2006/11/17
The Democracies Online wiki provides a quick overview of SMS pros and cons and describes how SMS was used the Philippines, Lancashire, Bristol, and South Korea.