Peter Manzo, a civil rights expert at UCLA and the Advancement Project, ponders on the SSIR blog whether the march -- a bedrock advocacy tool in the 20th century -- still has relevance for advocates. Manzo and others suggest that cell phones may be better suited to the way people live, work and communicate -- particularly in the developing world.

Even web-centered advocacy, Manzo notes, is confined mostly to the well-off and well-educated. Cellphone penetration, however, is a market trend that is seeing its biggest gains among those whose voices are least heard and would find it hardest to find time and money to participate in a march.

You may recall that the ONE Campaign has made forays into cellphone-based advocacy, at least on the citizen engagement end. Bono used to invite concert-goers to hold up cellphones (lighter style) and text him to be added to the ONE Campaign during U2 shows. But for cellphones to replace marches in any meaningful way, they'll have to do more than sign people up to a mailing list. Marches are powerful demonstrations of solidarity (think Solidarity in Poland) and collective resolve to those in power.

The sense of steely resolve that participants in a march find so heartening and opponents find so nettlesome comes in large part from the fact that many people are sacrificing time and money to speak for a cause. Cellphone advocacy -- which has the potential to pull many more people together over a greater distance -- takes some of the luster off of "speaking out" simply because it is easier. You can already observe this if you talk to Congressional staffers: there is a hierarchy of meaningful constituent feedback, and digital methods hold the lowest priority.

But these are hurdles, not necessarily roadblocks. It may be that as cell phone technology gets cheaper and begins to interact with web-based advocacy more easily as technology interfaces improve, cell phones will allow more strategic, "just-in-time" marches or similar face-to-face advocacy not possible with current organizing tools.

The march is certainly on the wane; I'd be surprised if it's not resurrected in one form or another.