Android phones are starting to appear nearly free, but everybody (really everybody) seems to be carrying an iPhone nowadays. People don't even use it for anything but for phone and SMS; but that tells a lot about how strong it is as a phone brand now.
Despite knowing only two people with iPhones (brother and flatmate) and nearly a dozen with other smartphones, it still amazes me how 95% of the phones I see on the Tube are iPhones. London is more affluent than the rest of the country, however.