Due to a planned reinstallation of a virtualization server, nightly builds will stop updating for a while. At the moment all build servers (except for MacOSX) are hosted on a virtualization server at Contuitus Net Research AB. This server is now in the process of being upgraded and will also change underlying virtualization platform.
Apart from not seing updates in nightly builds for a while, most users should not see any effects of this.
The last update of the nightlies will be tonight, and in the best of worlds everything should be up again by the end of the weekends.