My newest site was in the sandbox just recently. Basically Google drops your site way down in the search listings, but you get out of it fairly quickly. I was only in there for about 3 weeks.
The Sandbox (a.k.a. Sandboxing or the sandbox effect or the Google penalty) is a name given to an observation about the way Google ranks web pages in its index. It is the subject of much debate—its existence has been written about[1][2] but not confirmed and several observers state that they have observed the contrary.[3] According to the sandbox effect, Google temporarily reduces the page rank of new domains, placing them into what is referred to as its "sandbox", in an effort to counter the ways that search engine optimizers attempt to manipulate Google's page ranking by creating lots of inbound links to a new web site from other web sites that they own.
my website has just get into sandbox for one week, i feel so sad and desperate in seo but after i read the article about how to jump over from sandbox praise God Jesus, my website crownrentcar.net release from sandbox but i have to hard work again from zero to appear in first page on google serp. that's my experience my frend about sandbox. so you can go to google.com/webmastertool so you can find out . oke ;-)
sandbox is given to an observation about the way Google ranks web pages in its index. check this link en.wikipedia.org/wiki/Sandbox_effect