A few years ago, a PubMed search for "smartphone" would have yielded very few results. Today, a search on PubMed for "smartphone" yields over 400 results with the oldest reference being from 2005. Were you a smartphone user in 2005? Maybe you were still using a PDA.
Remember that the Apple iPhone was introduced in 2007 and that disruptive technology changed the world of smartphones and mobile computing. A PubMed search for "iPhone" currently results in over 170 publications.
Here are some of the more recent PubMed articles that will show up if you perform a search for "smartphone." The first 2 publications explore the diagnostic inaccuracy (not accuracy, but inaccuracy) of mobile apps that are designed to detect melanoma.
Diagnostic inaccuracy of smartphone applications for melanoma detection-reply.
Wolf JA, Ferris LK.
JAMA Dermatol. 2013 Jul 1;149(7):885. doi: 10.1001/jamadermatol.2013.4337.
Diagnostic inaccuracy of smartphone applications for melanoma detection: representative lesion sets and the role for adjunctive technologies.
Stoecker WV, Rader RK, Halpern A.
JAMA Dermatol. 2013 Jul 1;149(7):884. doi: 10.1001/jamadermatol.2013.4334.
Development of a Network RTK Positioning and Gravity-Surveying Application with Gravity Correction Using a Smartphone.
Kim J, Lee Y, Cha S, Choi C, Lee S.
Sensors (Basel). 2013 Jul 12;13(7):8879-94. doi: 10.3390/s130708879.
Development and feasibility testing of a smart phone based attentive eating intervention.
Robinson E, Higgs S, Daley AJ, Jolly K, Lycett D, Lewis A, Aveyard P.
BMC Public Health. 2013 Jul 9;13(1):639.