I was wondering if Microsoft is planning to release Office 2012 anytime soon ? Shall I wait for it or purchase Office 2011 ?
"traditionally" new Microsoft Office for Mac follow new releases of Microsoft Office for Windows:
The currently developed version of Microsoft Office for Windows is MS Office 2013. So you can expect the next version for Mac to be MS Office 2014 which should start shipping anywhere between late 2013 and 2014.