Just a note of praise to the Fedora distribution and the recent updates to Linux, X.org et al for getting display switching to work, at least on my laptop.
For years, it’s been a running joke that the first 10 minutes of every LUG presentation is spent watching the speaker (and too many helpful volunteers) struggling to get their laptop to properly display on the projector. (I’ve noted the equivalent at Rails meetings is everyone digging around in the bottom of their bag for the properly-matching MacBook-to-VGA adaptor.)
At the most recent CentraLUG meeting, I just plugged my running Thinkpad T61 laptop (running Fedora 10) into our ancient projector and had it immediately recognized! xrandr listed the VGA adaptor as 1024×768 and 800×600 (the higher format is interpolated — did I mention the projector was ancient?). The GNOME desktop menu options of System | Preferences | Hardware | Screen Resolution detected the display, also, and let me lower the screen resolution and mirror the two displays or align them side-by-side or top-to-bottom.
While I know other OSes have been doing this forever, this is a great milestone for Linux.