To go to the dictionary, click here, or type in http://google.com/dictionary. I didn't find any way to search directly from search.
Also, it doesn't have a refreshed look like the other Google services. It doesn't even have the new logo (see screenshot, click to enlarge).
I particularly liked the way it shows you examples of usage from the web that they index. At the bottom, it also shows the usual web definitions, which are pulled from various online encyclopedias and dictionaries.