I generally focus on the smartphone market here on ZDNet because that is what I use and what most readers seem to be interested in. However, the feature phone market is still relevant with staggering global figures that show over 70% of phones sold in 2011 were actually feature phones. Many, including myself, seemed to shrug off the Nokia World Asha Series 40 handset announcements, but according to this Forbes article feature phones are now more profitable than smartphones so it looks like Nokia's strategy of staying in the feature phone business may turn out to be a very smart move.
Many manufacturers that made feature phones in the past, including Motorola, Sony, HTC, and LG, have focused their efforts on the smartphone market. While Nokia is focusing on the smartphone market with Windows Phone, they are also very actively targeting the "next billion" with excellent devices like the Asha lineup that includes the Asha 303 and Asha 201. Nokia actually passed the 1.5 billion level this month and looks to rule this market in the future.
There is a report from Visiongain that discusses the low cost mobile phone market in detail.