If you look at the origins of the Apache ESME project, you will find that the origin was in a plurk (a micro-blogging site like Twitter) conversation that at some point moved to the SAP SDN wiki. The project then moved to Assembla and then Google Code.
The team involved was originally primarily made of individuals associated with the SAP community but has since expanded to include others from outside that community. The global team includes members from a variety of different nations ranging from Austria, India, Spain, Norway, Bulgaria, UK, Germany, the States etc.
Redmonk TV - The Making of ESME
In his keynote at the SAP UK & Ireland User Group Conference 2009, analyst Ray Wang compared ESME and Chatter.
ESME at Demo Jam Bangalore 2008
ESME at Demo Jam Berlin 2008
ESME at Demo Jam Las Vegas 2008
ESME - Interview with Dennis Howlett