I'm running QGis master v1.9.0 on xubuntu and the 'fetch python plugins' option is absent. This guy had this problem with vanilla 1.7.5 but fixed it by upgrading to 1.9.0 master. Nishant had this problem (version unknown); not sure if he fixed it but of the two solutions posted, the first (sudo apt-get install python-qgis) is already installed, and the second (uninstall, reboot, reinstall) changed nothing.
Arguably irrelevant but actually not: is there somewhere we can find the estimated landing date for QGis 2.0? If it's due tomorrow, for example, there's little point trying to debug a problem in the 1.9 master only for all such problems to be eradicated with the fresh 2.0 install... :)