This comes via Textually, although I've seen mention elsewhere as well. According to a report on C|Net, mobile industry executives are complaining that there are too many operating systems available for mobile phones.

Vodafone, the world's largest mobile phone company in terms of revenue, has been leading a push to limit the number of operating systems, declaring in November that it would eventually sell only phones that ran on Microsoft's Windows Mobile, Symbian Series 60 or Linux. For more than a year, NTT DoCoMo of Japan has concentrated on Symbian, a privately held British-based company in which Nokia of Finland has a nearly 50 percent stake, and Linux.

For the most part the different operating systems appear to mean little to the consumer, especially with recent reports about smartphone features meaning little to mobile phone users.