You can change the Revision Cloud lineweights, color or line pattern for the entire project by selecting Object Styles under the Settings menu in 2009 and selecting the Annotation tab then scrolling down to Revision Clouds category, pick the Override button under Lines and change the properties as requred. You can change the Revision Cloud properties per view by opening up the Visibility Graphics Override (shortcut VG) dialog window and picking Lines override button under the Annotation tab > Revision Clouds as well.
In 2010 you will find the Object Styles under the Manage ribbon Settings pull down.
Mel Persin, aia
Mel Persin, aia