From my experience I can say that there is absolutely no "google sandbox". I have had 9 new domains, all less than a month old, rank on the first page for some pretty competitive keywords. One of my sites is 29 days old and is ranked #1 out of 47,000,000 results. Some people might say this is the "reverse sandbox" effect, I would like to mention one of my sites that has been page one in the serps for over a year, was number 8 on the first page within 2 weeks of creation. I guess it's possible google may sandbox new sites that are in highly competitive, or fraud ridden niches. However over 2 years I have absolutely never seen any type of new domain sandbox effect.