In an interview with Pocket-Lint, Steven Walker, head of global marketing at Sony Ericsson, confirmed that SE is focusing primarily on Android when it comes to handsets. Sony Ericsson has always produced nice hardware, centered around the media and picture experience, but until Android, the OS used, Symbian UIQ3 was not up to the task of building a true smartphone.
Walker underlined that he sees Android as one of the top players in the game and said the following about their decision to stick with Android: “We need to do this so that there will only be a certain number of eco-systems that will prevail. Developers won’t develop for 17 eco-systems. Consumers won’t choose between 100 different eco-systems. In the end only a certain number will prevail”. While he does not exclude the possibility of Windows Phone 7 handsets being released, there are no clear plans as of now.
He also commented somewhat on the fact that the upcoming Xperia Arc will ship with 2.3 Gingerbread from the start as opposed to the Xperia X10 that's still waiting for Froyo: "It’s the first question people ask “which version of Android is it on”, but in a year’s time I don’t think it will be the first question people ask, it will be in the list of questions but it won’t be the first question”. I think Walker hasn't learned the lesson that the X10 should have provided them. While it's true that most people won't care that much if they're on the newest release or not, endlessly delaying an OTA until the phone is obsolete is unacceptable to at least a decent chunk of users.
Their Xperia Arc is a really nice device from what I can tell, but I just hope they don't abandon all their older handsets for their new flagship unit.