Ready or not, another integration of Google's products has occurred. Now, when Google Maps users go looking for a terrain view, they won't find it (easily -- see correction); instead, a new option that essentially functions as a link to Google Earth is at the ready.
People who don't already have Google Earth installed will in fact be unable to proceed until they download a browser plugin, and it's almost certain that this change will disappoint some folks. A 3D pan-and-zoom experience is likely to be seen as overkill (and a resource hog) if all that's needed is a rough idea of how some land rises and falls.
Google Earth is definitely a more entertaining product than a simple terrain view, however, and people who weren't aware of Google Earth or just weren't in the habit of using it may appreciate the update.
Also, it's fair to say that the average computer of 2010 should be more capable of handling Google Earth than the average computer of 2005 (the year Google Earth launched).
All in all, Google has at least brought its product line closer together and succeeded in upping the eye candy factor of Google Maps. Traditionalists can still enjoy the same old "Map," "Satellite," and "Traffic" overhead views, as well.
CORRECTION: The terrain view has been tucked under the "More" button, and so while people (such as this writer) may overlook it, Google hasn't removed the feature.