Yes, but not as integrated as you want it to be. First import your Domino project into RTC by using Project Explorer, right click/Import. Choose "File system" and specify the location of your On-Disk project. Then you can upload your code into an existing repository workspace.
So you will still have to use the Rational user interface for source code control.
I noticed that "see pending changes" wont work as expected in RTC3.0.1. It will take some seconds before a refresh has any effect. So if you cant see your changes in RTC, wait a few seconds, then hit refresh.
Reminder to self: should create a blog post about using RTC with Domino Designer