I think the Fedora policy requires more of a commitment from maintainers than I can offer. In any event, I know RStudio Server can be built from source on Fedora and that it works but it needs a lot of detailed attention to turn it into something that will make it into a release. It has a few dependencies - gwt, for one - that aren't in Fedora so their source needs to be packaged in the source RPM.
There's also the question of upstream - they have a build process that makes usable binaries for openSUSE and Fedora but only support the server on Debian, Ubuntu, RHEL and CentOS. I did get them to fix some issues when their run-time dependencies messed up a Fedora R upgrade, but I don't know if they'd actively participate in a distro packaging effort. They'd need to be asked.
All that said, this is a good time to start such a project, since Fedora 21 is about two weeks away from release. I have a COPR project opened but haven't put anything in it yet -
https://copr.fedoraproject.org/coprs/znmeb/rstudio/