We are about to develop a Check In module with Action and/or SMS integration for a client and are interested in the status of this module. Do you have code that could be released which we might be able to collaborate on? We'd be happy to help move this project forward, and think that it is an important module space. Please let us know how we might be involved.
(Ps. as an aside, we're looking at a slightly different use case: check ins are not going to be node-specific in our scenario).