Yes, this is part of the digital divide that still exists in some parts of America; mobile is the only way some accomplish internet access.

This is an overview from the April ’09 Pew report that outlines mobile activities. It doesn’t note specific applications, but you might be able to glean insight nonetheless. Note: this information includes all surveyed segments, not just Latinos.
http://j.mp/4pNRTC

Your other question, about less educated / low earners, is a good one. The “Latinos Online” report simply reveals the data. It doesn’t draw conclusions. Unfortunately, I don’t have much to offer beyond guesswork. There could be a connection here with mobile use, since that appears to have been adopted more broadly by those surveyed. Internet access via mobile device is pretty common now, much more so than in ’06. Mobile Internet service is still pretty expensive, but mobile hardware is generally cheaper than laptops and desktops. I suppose an argument could be made that Internet via mobile devices is a better value than PC-based Internet, so if you’re going to choose one or the other, maybe mobile gets the nod? Again, total conjecture.