AutoCAD 2010 introduces a couple of refinements for working in Layout (paperspace) viewports.
Rotate Viewport, Rotate View!
Previously to rotate a layout view you had to rotate the viewport UCS, then set the current view to match the new UCS, then invariably fix the zoom to extents which happened as you did those.
In AutoCAD 2010 you simply rotate the viewport using the same rotate command used for geometry. The contents of the view, UCS and objects, will rotate with the viewport frame.
This behaviour is controlled by a new variable: VPROTATEASSOC. When set to 1, the view within a viewport is rotated with the viewport. When set to 0, the view remains the same when the viewport is rotated (legacy behaviour).
Change space Paper/Model:
Ever noticed something in a layout viewport, zoomed in, double clicked into the viewport to fix it then found there is no way out? The usual technique is to double click outside the viewport but you're zoomed in so far you can't see "outside". You can't zoom out because that just zooms within the viewport, if you change to Modelspace & back you end up where you left. There are command line ways out of this but 2010
adds restores a UI option when Layout Tabs are not displayed.
AutoCAD 2010 has a PAPER/MODEL change space control to help you out of that situation by toggling between Model & Paperspace while remaining in a layout. In 2009 having Layout Tabs hidden removed this control from the status bar.
UPDATE 2009-02-18: Updated in response to comments