Could work in many cases. I've always liked this concept for email in a similar way. I'm already in my email all day on all of my devices and utilize it in a number of ways. Let me stay in my email and you don't have to entice me to your site or app to actively use your service. I like the way http://www.statlogger.com has integrated both SMS and email in this way. I'm trying something similar with http://tuduli.com (email-based to do list). SMS could work, too.
Title's a tad misleading but kind of catchy :)
TL;DR version is a project about solving tech gaps by redesigning useful online services as SMS products. It's a pretty fun UX challenge to do, thought I'd share