Confirming. The challenge is how to find them, because [1] doesn't mention any similar name for a distinguished folder ID. Nonetheless, Google helped here, and after seeing one example how to do that, one can find appropriate value in Types.xsd, which is defined for Exchange 2007 servers too. The value is:
   publicfoldersroot
It's more or less logic, though I would expect to see it in [1] too. There are some typos as well, but I noticed more on other places in their documentation, so not a big deal and surprise.

[1] http://msdn.microsoft.com/en-us/library/aa580808%28v=exchg.140%29.aspx

Created commit 2a61b5b in ews master (3.7.5+)