To demonstrate this great service, I have taken the Silverlight Ink SDK Sample, uploaded it to Silverlight Streaming and then embedded it on this blog using an IFrame, like this:
<IFRAME src="http://silverlight.services.live.com/invoke/34348/InkCanvasSample/iframe.html" frameBorder=1 width=400 scrolling=no height=300></IFRAME>
The highligthed part is the key: it specifies your Silverlight Streaming application ID and name of your app. For more information about Microsoft Silverlight Streaming, visit http://silverlight.live.com/.
Here is the sample for you to try out: