Mac Rumors reports that research firm DisplaySearch today released the results of its estimates of mobile PC sales for the second quarter of 2011.

The study includes both traditional notebooks and tablets, and Apple was able to ride the strength of the iPad to the top of the list with 21.1% of the market on 13.6 million units shipped. Apple comfortably topped second-place HP, which came in at 15% share with 9.7 million units shipped.

  Apple Tops Worldwide Mobile PC Shipments in Q2 2011 with iPad Included