I've been attending the Microsoft Convergence 2009 Conference this past week. The conference is focused on Microsoft's Dynamics business software but there were some Office and Server sessions. I sat in 2 sessions about OCS 2007 R2 just for diversion and because of my interest in OCS and got to ask the question: "Considering the many servers involved in a typical OCS implementation, Will Microsoft release a OCS small business edition?" The answer: "Based on MVP and other input we are definitely talking internally at Microsoft about the possibility of an OCS small business option."
He also noted that currently it is "possible" to have a single server implementation of OCS and noted some of the missing features that make OCS "not quite fitted" as a complete pbx replacement at this moment.