I am aware of this question, but the services don't seem to have support for receiving SMS messages to set tasks. Ideally, I should be able text a certain number something with the format "stop by Grandma's at 4pm tomorrow" and expect it to relay the message back to me at the time specified.
Remember the Milk has the Smart Add feature which "intelligently" finds the time in the message, figures out what I mean by "at 4pm tomorrow", and extracts it from the name of the reminder. RTM allows setting reminders by email, but my phone (as well as many others) has trouble correctly sending and receiving emails as SMS messages.
Does anything like this exist? If not, would it be something useful to build and release on my own? Thanks.