Recently I've started smallqtcore project, which it available at https://code.google.com/p/smallqtcore/.
Basically it's native port of QtCore, QtNetwork and QtXml to the Symbian without using OpenC. If for some reason you can't/don't want to use OpenC, RVCT build 686, need to start from S60 3rd MR, etc. you can use smallqtcore.