Samsung, Lenovo (OTCPK:LNVGY), and Yulong (Coolpad) are each estimated to have ~12% of the market. In Q1, Samsung had 18.3% to Lenovo's 11.3% and Xiaomi's 10.7%.
Xiaomi has gained ground by offering Android phones with high-end specs at mid-range prices. Successful viral marketing campaigns and a popular custom Android UI (MIUI) also haven't hurt.
The company just launched a new flagship (the MI4) that starts at $320 unsubsidized, and features a 13MP f/1.8 camera and 5" 1080p display. It's counting on former Google exec Hugo Barra to spearhead an international push; Canalys estimates 97% of Xiaomi's Q2 shipments went into mainland China.
Xiaomi's "borrowing" of ideas from Apple and other rivals has produced controversy. Not only does Xiaomi's hardware take many design cues from the iPhone, founder Lei Jun has cultivated a Steve Jobs-like image, and ended his MI4 launch presentation with a slide prefaced by Apple's "One more thing..." catchphrase.