Oh well, my initial gut instinct was right. Forgot to set the user against the anonymous connection via http://hanaserver:8000/sap/hana/xs/sqlcc/
The indexserver trace file will also give you a pretty clear hint!
[5008]{-1}[-1/-1] 2014-04-19 08:04:52.855679 e XSRequestHandler RequestHandler.cpp(00564) : exception 1: no.2 (XSEngine/Util/ConnectionPool.cpp:126)
could not create db connection from sql connection configuration hpl.missioncontrol.services::anonConn, username not set
exception throw location: