Either as a deployment platform or as an area that you are investigating for a tool/service.
Or maybe you're just adding Azure integration to an existing product.
I'd love to hear any opinions/experiences you might have had, or maybe if you're considering it what you find attractive about it or what puts you off.
I'm not, but http://www.microsoft.com/bizspark/ is a program that gives startups 3 years of product licenses, including some Windows Azure and SQL Azure credits. I don't know too much more about the program, but its at least worth checking out if you're thinking of using Azure.
Bizspark is like a pusher for startups. Why anyone would start off doing anything using Microsoft tools is beyond me. Everything you need is out there and its free.
I am aware of one that is but so far they're in stealth mode. Most other firms I've asked about that have had some derisive commentary about building on Windows.