During Q2 2012, smartphone penetration continued to grow in the US, with 54.9% of US mobile subscribers owning a smartphone as of June 2012. This is according to the latest research from market research firm Nielsen, which found that two out of three Americans who acquired a new mobile phone in the last three months, opted for a smartphone instead of a feature phone.

Like comScore, Nielsen found that Google’s Android continues to dominate the smartphone operating system (OS) landscape Stateside, with a majority of smartphone owners (51.8%) using an Android-powered handset.

Over a third (34.3%) of smartphone owners use Apple’s iPhone, while owners of RIM’s (Research In Motion’s) BlackBerry smartphones represents another 8.1% of the smartphone market.