I use this for Google sandbox and other important tools which are help in SEO http://www.searchenginegenie.com/sandbox-checker.htm
I would describe the sandbox effect as a type of penalty, i.e. an imposed ranking restriction, specifically for relatively new sites. Getting sandboxed typically leads to a substantial loss of mostly all Google organic traffic. This can have a significant impact. Wouldn't it be good to be able to confirm with the search engine (e.g. Google) what the sandbox / penalty status is? At present there is no means to confirm this (other than interpreting traffic and ranking changes). If you have been sandboxed or penalized, check out our campaign "Have I been penalized..?" which demands search engines to disclose the penalty status to website owners. Submit your case study there.
Google Sandbox is one of the most weird experience for Website owners. The Symptoms that a blog is facing Sandbox is the Homepage will not b visible at Google or any other search Engines, your Page rank will be N/A.
If your site is in google sandbox it means that they were observing your site, if you site is according to TOS of google then they will release it.