I haven't put the RC on my laptop yet - too close to Tech Ed for me to mess with important stuff - but I liked this summary from Tim Sneath of what an RC means, and what you should be looking at as a developer. Make sure your application runs properly on Windows 7 to start with (and if it runs on Vista, it will almost certainly run on Windows 7), then look at adding goodies to it that take advantage of what the OS has to offer. He even includes a link to Code Pack. Check it out.
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