The Omni Group has posted a public beta of OmniGraffle 4, a general purpose Mac OS X diagramming tool and my UML editor of choice. New features in 4.0 include Bezier curves and improved import and export to/from PICT and Visio. OmniGraffle ranges from $79.95 to $149.95.
Gentleware has released Poseidon for UML 3.1 a Unified Modeling Language CASE tool based on the open source ArgoUML. Poseidon for UML integrates with NetBeans/Forte/SUN One Studio, and features generation and import of Java code. This release Version 3.1 adds UML 2.0-compliant state diagrams, copy/cut/paste of diagrams and semantic model elements, and customizable UMLdoc for HTML. Pricing depends on which features you want and ranges from $249 to $875. Upgrades from 2.x range from $149 to $449.