For some time now, development on rdesktop has been stagnant: many patches and ideas are submitted, but changes in the software have been absent for several years now. There is also a conflict between the Debian & Ubuntu releases of rdesktop regarding keyboard handling that was never resolved. FreeRDP redoes the whole keyboard-handling process, and also adds support for protocol content hosted by Windows Vista & newer codebase systems.
As for Vinagre client, it is supplanted in functionality by Remmina: that software is already approved for Ubuntu use, and the 0.8 version released on July 10, 2010 supports FreeRDP, VNC, NX, XDMCP, and SSH; as well as using IPv6 addressing.