Edit 5/21/2009: The G.E. plugin is killing performance on my PC and since it wasn’t too impressive, I have removed it from this post.
It is now incredibly easy to embed Google Earth into a blog or website, with the results that you see (maybe) below. However, I’m not sure how effective of a tool this really is. On the one hand, it allows a viewer to explore information without actually having Google Earth installed (although the plugin must be installed in the browser). But on the other hand, the functionality is limited compared to the full version. In particular, I wish that it allowed for a tour to played of waypoints, the way that it can be done in the full version. It also appears that photos within waypoint captions are not being displayed at all
In any case, if you want to embed a KML/KMZ file of your own blog, this tutorial is really easy to follow.