The sandbox has been hampering SEO efforts as far back as before April of 2004. Our first official coverage of what was later to be termed as the "sandbox effect" was on April 17th in an entry named New Sites = Poor Results in Google which linked to the first large thread on the topic at WebmasterWorld. Since then we mentioned sandbox here over 25 times.
A forum individual who pretty much has been dedicating most of his time towards uncovering the sandbox theory has developed a tool named Sandbox Detection Tool which does its best to "calculate factors commonly associated with being under Google's "sandbox" penalty." The inventor of the tool, randfish, removed the link to this tool temporarily while he makes some minor modification based on the feedback at an SEO Chat Thread.