How is Yahoo Messenger faring against its competitors?

Yahoo Messenger is soon set to topple AOL’s AIM as the leading IM service in the US

AIM
User base in US: 30.2 million
Growth past year: 2%

Yahoo Messenger
User base in US: 27.7 million
Growth past year (US): 19%
Worldwide user base: 94.3 million
Growth past year (world): 30%

World Leader in Instant Messenging: Windows Live
Leader in American Market: AIM