Truphone issued a couple of press releases today. The first release announces full interoperability of IM with MSN Messenger, Yahoo! Messenger and GoogleTalk in its iPod Touch and iPhone applications. They have also integrated Twitter into the TruFriends view of the Truphone application.
In the case of GoogleTalk users can also make and receive voice calls using the Truphone application. Similar voice capability is in the work for users of MSN Messenger and Yahoo! Messenger.