In what he said is his last keynote as a full-time employee of Microsoft, Bill Gates hit on some of his common themes as he spoke to what he called his crowd -- developers -- at the company's annual TechEd conference on Tuesday.

"It's the first time I've really changed my career since I was 17 years old," he said with what appeared to be a genuinely reflective smile. His talk was mainly a relatively stoic, standard Gates keynote that included references to how much the industry's changed since he co-founded Microsoft with Paul Allen more than 30 years ago.

But while he touched on Gates favorites like more natural human-computer interaction and easier software development for everyone, he focused on how Microsoft looks at the changing software development world today.

Most significantly, Gates talked about how modeling will transform software development for Microsoft customers, especially in how the software development lifecycle is managed. "Over time, code gets complicated, and you want to be agile and change it," he said. "This is definitely an area that's open for improvement."

He brought Microsoft technical fellow Brian Harry on stage to demonstrate some of the progress Microsoft has made in its modeling strategy, code-named Oslo. Microsoft intends to deliver some of the first test versions of a modeling language, repository, and tools by October at this year's Microsoft Professional Developer Conference.

Harry demonstrated new tools called Architecture Explorer and Architecture Layer Diagram that allow architects and developers to work to make sure code stays in line with architecture guidelines. Architecture Explorer allows architects and developers to visualize application logic in current code, while Architecture Layer Diagram shows what the application logic should look like. The applications also allow developers and architects to validate actual code against the diagram and create a technical policy to validate code before it gets checked into the system.

"You can take an application that you've never worked on before, take a modeling tool to parse that application and show you a model of it, make changes, and make sure it validates against the design," Harry said. In a later question and answer session, Gates said that Microsoft would begin supporting the standardized Unified Modeling Language for object modeling in Visual Studio 10, which is the next version after the current Visual Studio 2008.

S. Somasegar, senior VP of Microsoft's developer division, showed off Silverlight 2.0, a beta of which is being released this week. Silverlight allows .Net developers to write applications for the Web. "When we think about application development at Microsoft, we really think of it in the broadest sense, and we strive to give you a set of tools that allow you to learn once and then use your expertise wherever you want to go," he said.

Gates also talked about how Microsoft is looking to mainstream robotics development techniques, highlighting that robotics is at a stage not unsimilar to where the PC industry was when Microsoft first started. He smiled when a robot called the "Ballmer Bot" that had been developed with Microsoft's Robotics Development Studio walked on stage, complete with an LCD screen face of Microsoft CEO Steve Ballmer, chanting "developers" over and over again.

While Gates might not be around to see Microsoft become a robotics software powerhouse as a full-time Microsoft employee, the developers chant will likely retain much of the same relevance then as it has for Microsoft's first few decades.