As it was announced by Pentaho-Hitachi, version 6.1.01 was realeased on the 9th of april of 2016 in EE and CE editions.
Sourceforge.net: Data Integration, Business Intelligence Server, Report Designer, Pentaho Metadata and Big Data Shims.
There are lots of fixes: 179 of 180 issues have been resolved in PDI, 59 of 59 issues for the BI Server and 14 of 14 issues for the PRD.
These are the main improvements acording to Pedro Alvez: Services, ODBC, metadata injection, several steps improvement and enabling tests in the BI server from the PDI, this was lost since studio went down the tube.
Steps for upgrading must be the same as previously posted. If not I will get back to you and annote this post. [Which is very much unlikely].