Oftentimes I find something interesting in Google Maps and want to see it more detailed in Google Earth. You could try to repeat the search in Google Earth, but that's not the best idea.
To move to the same location click on "Link to this page", go to the address bar and copy the value of the ll parameter from a Google Maps address. Then type the value in Google Earth's search box. Here's an example:
http://maps.google.com/maps?f=q&q=Paris,+France&layer=&om=1&
z=14&ll=52.046737,-0.198269&spn=0.024229,0.080338
If you want to save some clicks, after clicking "Link to this page", add "&output=kml" at the end of the URL and hit Enter. A dialog will ask you to open or save a KML file. Choose to open the file in Google Earth.
There's even a bookmarklet that automates the process. Bookmark this link or drag it to your bookmarks toolbar. Next time you want to switch to Google Earth, just click on the bookmarklet.