In Switzerland and other countries in europe, there is already an App that's really popular and in some points better the iMessage.
WhatsApp is cross platform, meaning it exists for iOS, Android, BlackBerry and Nokia. No Windows 7 Phone yet.
It not free, but very cheap (.99cent) and sending Videos, Photos, Text, Location, Voicememos works exactly like iMessage. Its also got send and delivery icons (1 checkmark means its sent to the...