Mashable featured an interview with Melinda Gates (of the Bill & Melinda Gates Foundation) earlier this week entitled Tech's Responsibility to the Developing World.
The word she gave that those seeking to glorify the Lord using mobile ministry among the unreached of the developing world need to hear is this:
When it comes to issues in the developing world, an understandable concern is "technology creep," wherein organizations use advanced technologies even when a low-tech solution may prove a better option. To avoid this, according to Gates, one must understand what kind of technology certain people are likely to have, and work with it in a local context.
Sure, the iPhone and iPad can always do it better and with more flare but if you want to have impact among the unreached it's a lot wiser to look and see what technology the people you are reaching out to actually have and develop an outreach that lives within those constraints. Although every other person here in the U.S. seems to have an iPhone and/or an iPad that just isn't the situation among the least reached!
A beautiful iPhone/iPad app intended for people who make three dollars a day and can neither afford the device nor the internet service required to run the app doesn't help them a single bit. The only real help such an app provides for outreach is in raising funds for your ministry as you show potential funders what a neat whiz bang app you've produced (not something I would promote!). Alternatively, if your people group is the Japanese I'd highly recommend developing an iPhone/iPad app for your outreach like yesterday!
If you're really looking for impact and not just show, avoid the technology creep and start with the end user, the technologies they are using and how they are using them.
A couple short videos dealing further with the subject of appropriate technology and solutions are Computing on the Margins: Tools that Travel and Why Kenyans Do It Better.