The Google Sandbox concept used to be the idea that a new site couldn't rank well on Google until a certain time period had passed. Over the past two years, it's been debated, redefined, morphed and then largely something I'd say people have moved on from. Naturally, we need something else in its place -- and the -30 penalty seems to be the likely candidate.
Drop 30 Points in Google? Meet The "Minus Thirty" Penalty? over at Search Engine Roundtable covers how some people are saying they always rank at number 31 on Google, with their impression being that Google must be placing some type of penalty to kick them past number 30. Google Says "No Ranking Soup for You" at Threadwatch has a similar roundup of forum discussions, along with more debate.