Actually, enabling file sharing was one of the most poplar demands made by Gtalk users. This facility has further enhanced Gtalk which is in competition with Yahoo! Messenger, which had this facility way back in Aug 2005, ie exactly an year ago..
File sharing through local IM have definately got an edge in safe file sharing, but at the same time, it has been hotly argued and debated that P2P file sharing makes it possible for malicious users to distribute pirated copies of software more easily and effectively. Its very easy for users to transfer large files in one go. This method, although very useful for Linux downloads, is a virtual nightmare of music companies, artists, software giants..
Did you know, that apart from Yahoo! IM and Gtalk, there are several other clients which we dont know?