Stands for "mobile learning" and refers to the usage of training programs on wireless devices like cell phones, PDAs, or other such devices.
www.conferzone.com/resource/glossarymn.html

Mobile learning. Learning that takes place via such wireless devices as cell phones, personal digital assistants (PDAs), or laptop computers.
www.itslifejimbutnotasweknowit.org.uk/lt_glossary.htm

M-learning is the followup of E-learning which on his part originates from D-learning (distance education). The rapid growth of information and communication technologies makes it possible to develop new forms of this education. Today's students knowledge of mobile devices makes the entrance of mobile learning (M-Learning) possible.
en.wikipedia.org/wiki/M-learning