If you could not make it to Las Vegas to attend MIX09, you can take comfort in the fact that you can still watch over 100 presentations online that are powered by Silverlight. They are also available for download in WMV, MP4, WMA, MP3 and some in PPTX formats.
I wish the listing also had the duration and a precise summary of contents. I watched Search Engine Optimization (SEO) for Web Developers (13.45 minutes) to "learn SEO best practices and proven techniques". The description was a little far-fetched as it covered only URL Rewriting (with IIS 7) significantly. Ofcourse 13 minutes is too short a time.
I'm keen to watch "Building High Performance Web Applications and Sites" (59.23 mins.) and have it next on my list.
Which presentations did you like?