You might want to check out the Qt Components thread & wiki article. There are quite a few applications already using Qt Components on Fremantle and the the Qt Components packages are available from Extras.

There are basically two component sets - CSSU ones that are almost identical to the Harmattan ones - and modified components that run with the old Qt version on Fremantle PR 1.3 without CSSU (they support only QML 1.0 and have a custom namespace).

Also, from my experience a while ago, the non-CSSU components seemed to be having a few layout issues that were not present on CSSU. Also, the base theme is not complete so some icons available on Harmattan might be missing.