The docs say that it is still /template/global/community.ftl:
But that file isn't listed in the Create Custom Template list in Admin.
I think it may be /soy/places/place.soy with 6.0.
I actually received a response from Jive support after opening a case. Thought i might share it as well:
These pages are located in the .soy files, check out
For more information about soy templates check out Guide to using Google Closure Templates in Jive 5.0 / 6.0 and SOY File Changes. Let me know if you have additional questions.
There is a second template.ftl that you will need to edit in Jive 6, located in /template/eae/template.ftl This is just for the Overview and Activity stream pages.
This template.ftl calls /soy/welcome/welcome.soy and /soy/eae/activity_stream.soy.