Thornton and Houser were among the first to show the potential for cellphones for vocabulary learning back in 2004. They sent out SMS messages to their students with new vocabulary, and made sure that each item was received multiple times by their participants. I don’t think (but I could be wrong here) that they made use of spaced learning by increasing the time interval between each exposure. Flaschard software is excellent at that, and now there are programs for use on cellphones. This could potentially be excellent as you are likely to have your phone with you when it is time for your next rehearsal. Here is one such program (www.flashmybrain.com) but there are many others.