On the face it would emerge that this is so. New sites are characteristically taking a long time to get indexed and even longer to show up in the search results. So hence, the sandbox theory. Let’s examine some probable reasons and more prominently, our reaction to it. The most apparent possibility is that because of the explosion of spam on the engines, Google is checking all the links to these new sites. Google it seems is solemn about link farms, and anything that smacks of that may take some time to get indexed.
It is a very big index, some say approaching capacity, though I doubt that will turn out to be true and it is a huge task to keep it existing and free of extraneous search results. There are other thoughts out there, and plot theories abound, one being that it is a wickedness plot to force newer sites in search of traffic to resort to paying for Google Adwords.