One of the new features touted by Apple in its upcoming OS X 10.9 Mavericks operating system is the multiple display management features that allow better integration with full-screen applications. However the new features come with other changes that, for some people, and especially those with more than two displays, may be a bit of a hindrance.
Recently an individual by the name "MrThaiBox123" posted on YouTube a small look at the new desktop management features in the current developer preview of OS X 10.9, which outlines the benefits as well as the drawbacks of these changes.
Overall, it appears that while Mavericks does allow use of additional monitors when one application is in full-screen mode, implementing this now prevents applications from stretching across monitors, and may also result in a bit of a jumble of different desktops among the various monitors you are using.
The video is a bit of an extreme look, since it uses a six-monitor configuration, and perhaps the features may be more straightforward with a more typical two- or three-monitor setup, but it does give an idea of some of the limitations some people may encounter.
Fortunately for those affected by the drawbacks, from the video it appears you can toggle this behavior on and off, perhaps via hidden settings if Apple does not give a preferences setting for it. There also may be additional hidden settings that can be used to customize the behavior even more.
Keep in mind this look is only at the developer preview, and as Mavericks gets closer to its release later this fall these features may change.