the exchange alternative market has been thriving for long, comprising of "hosted exchange" companies and pure alternatives like postpath. if you do a google search on "exchange alternative" the company which appears below postpath is HyperOffice . they have a compelling solution (integrated email messaging and collaboration)and they recently launched HyperMeeting , a web conferencing solution integrable with HyperOffice, also making them an interesting player in the "complete collaborations" or "unified communications" market.