As described in the IBM XPages for Bluemix documentation, Building applications with the IBM XPages runtime for Bluemix, you must have version 901v00_13 or later of the XPages Extension Library or newer to use the integrated Bluemix tools for Domino Designer.
It will be a fun week with lots of news about IBM XPages for Bluemix. So stay tuned!
IBM XPages for Bluemix documentation
Building apps with the IBM XPages for Bluemix runtime
Getting started with IBM XPages NoSQL Database for Bluemix
Creating apps with the IBM XPages Web Starter
For more information about Bluemix see also Out of the Blue: Getting started with IBM Bluemix development by Oliver Busse.