It's becoming more commonplace to run software simulations of electronics device designs and packaging for thermal analysis. PCs contain the speed and graphical user interfaces that allow for complex heat simulations at relatively low cost. Software simulations are possible at the device level, the pc-board level, the packaging level, and even the system level. Hotspots on device die and pc boards are more predictable.
Companies like Cadence Design Systems, Flomerics Ltd., Gradient Design Automation, Magma Design Automation, and Mentor Graphics offer advanced software products that let designers complete transient simulations quickly enough for electrical and thermal design considerations to occur concurrently. Today, device and package designers use these products early in the design cycle to ameliorate heat issues that may crop up later in the device production process. Studying thermal issues early in a chip's design-to-production cycle minimizes overall production costs.
Software tools aren't heat-management solutions on their own, though. Understanding the thermal/fluid physics of a device's model and its placement on a pc board, in a package, and within a larger system is still a cumbersome and inaccurate process. Nevertheless, software tools and the development of thermal-simulation software standards are getter better, which lends a huge hand to design engineers.
Software tools can only help in understanding and predicting heat patterns and flows. They don't show how heat can be removed, which is ultimately the job of a cooling system and its components.