It's a common functionallity that you always need. I have done this myself before this way:

if(System.Windows.Browser.HtmlPage.IsEnabled == true)

It have worked great in my projects, but today I found out that this isn't the best approach, as it doesn't always work. I found out when I read this blog post:

http://blogs.msdn.com/delay/archive/2009/02/26/designerproperties-getisindesignmode-forrealz-how-to-reliably-detect-silverlight-design-mode-in-blend-and-visual-studio.aspx

Go ahead and read it :)

I just read this really well written and interesting document by Nikola Mihaylov.

"Nikola Mihaylov is a Software Design Engineer in Test at Microsoft, working on the WPF/Silverlight tools for Visual Studio. Nikola’s first Silverlight game topped the http://silverlight.net charts for 2 weeks after its v1.00 release in 2008."

It gives you a great idea of how to build a Silverlight game, and for the people who have already build games on their own, it's still good reading. I mean, we all want to learn something new all the time, right?

The document can be found on Nikola's blogpost here: http://blogs.msdn.com/nikola/archive/2009/02/05/anatomy-of-a-silverlight-game-avoid-common-mistakes-when-building-silverlight-online-games.aspx?CommentPosted=true#commentmessage

- Enjoy!

I just found these really nice tips from Scott Hanselman himself. It's sort of a "check-list" for what you need to know before going to the stage.

http://www.hanselman.com/blog/TipsForPreparingForATechnicalPresentation.aspx

http://www.hanselman.com/blog/11TopTipsForASuccessfulTechnicalPresentation.aspx

http://www.hanselman.com/blog/TechnicalPresentationsBePreparedForAbsoluteChaos.aspx 

Enjoy - and thank Scott for the tips :)