Google's Android , BlackBerry, Apple iOS Top Mobile OS Rankings

Research in Motion's (RIM) BlackBerry platform and Apple's IOS4 were the top mobile operating systems in the month of May, according to a data released by comScore on Thursday. The data disclosed that even as both OS stood at the top position, they had lost some ground to Google’s OS Android. The data has not included the iPhone4 that was launched in June. The iPhone4 has been dubbed as Apple’s finest device ever.

That data, however, does not include the iPhone 4 launch, which debuted in June and has since been dubbed Apple's most successful product launch ever.

RIM had 41.7 percent of the market in May, followed by Apple at 24.4 percent, and Microsoft at 13.2 percent. All three saw declines from February, though. RIM was down about 0.4 percent, while Apple dropped 1 percent, and Microsoft lost about 1.9 percent.

According to the comScore report, Microsoft's mobile operating system was No. 3 with 13.1 percent of the market, but it had the biggest drop, at 1.9 percentage points, among the five biggest platforms.

Palm was No. 5 with a 4.8 percent share, down 0.6 points. After struggling to compete with larger rivals, the Sunnyvale maker of the Pre and Pixi smartphones was bought last week by Palo Alto computer maker Hewlett-Packard for $1.2 billion.