The Mac software maker Omni Group has just announced the availability of the first public preview of OmniGraffle 4.0, the new version of the premier diagramming application for the Mac. Among its many new features, Omni announces support for SVG export so that OmniGraffle documents can be displayed beautifully at any size, whether you're viewing them on the screen of a mobile phone or on a large print banner. OmniGraffle 4 is expected to ship this summer.