The best Android phone Nexus One has stop its production and online store to avoid direct competition with its handset partner. The other reason is the low percentage sales figure since its launched in January. Google Nexus One could have been late to reach the market. If it is released at the same time as Apple iPhone, it could have gain much momentum now.
Although the Nexus One is no longer selling online, but the Android OS is still going on and use by hundred thousands of mobile users world wide and it will continue improving until it can par with Apple OS. It could be soon or later.