Perhaps it's a matter of cognitive style.  I tend to be a visual learner, preferring text and graphics to audio input,* so I feel under-qualified to judge whether mission-based organizations should invest their resources in podcasting

Although I'm a techie, I have an odd streak of Luddism when it comes to new media.  I may turn out to be immune to the charm of podcasting, but that would not surprise my loved ones, in that I stopped watching television in the late 1970s.

However, in theory, I do like the idea of enabling individuals and organizations to be audio broadcasters, operating independently of traditional gatekeepers such as major networks.

Though unable to forecast whether podcasting will turn out to be the Next Big Thng, I suspect that it will greatly appeal to the generation that receives most of its news from television, talk radio, and hip hop music. This generation and its successors - unlike yours truly - is the future. Therefore, it's important to make sure that nonprofit and philanthropic organizations are briefed on the basics of podcasting, and can make an informed decision about whether it is likely to be a powerful channel of communication with stakeholders.

For a basic review of podcasting:
Wikipedia's overview article

For an introductory podcasting manual:
CampaignAudit.Org

For information on iPod, a line of digital audio players that are used for creating podcasts:
The official Apple web site

For reflections on podcasting, especially as it pertains to the digital divide:
Andy Carvin's blog, ICT Etcetera


For an introduction to podcasting for activists:
Audio Activism

For updates on smart mobs combined with mobile podcasting:
Mobcasting

For an overview of a spin-off that is developing a business model for podcasting:
Beercasting




*  In the past ten years, I have been working on enhancing my audio learning by listening to National Public Radio and BBC Radio News at least a few hours each day.  I've heard a lot of interesting information and commentary, but I can't boast about a high rate of retention.