On August 25, the Green Party of the U.S. Outreach & Exploratory Committee received this response from Jill Stein. The Committee had asked potential presidential candidates to fill out a detailed questionaire. This does not mean that Stein has committed to seeking the Green Party presidential nomination, but it shows she is thinking very carefully about it.
Jill Stein is a physician in Massachusetts who has been a leader of the Green Party in her state for over a decade. Here is her wikipedia page. Here is her web page, which has a link to her 2010 gubernatorial campaign page.
Stein raised $150,000 for her Massachusetts gubernatorial run in 2010. She probably has the organizational savvy to qualify for primary season matching funds if she runs for the Green nomination. No Green Party presidential candidate except Ralph Nader in 2000 has ever manged to qualify for primary season matching funds. The federal law requires raising at least $5,000 in each of 20 states. The period for raising these funds ends after the particular party chooses its presidential nominee. The Green Party still hasn’t set the date of its 2012 presidential convention, but it is likely to be in July or August. UPDATE: here is Kent Mesplay’s response. Mesplay is also seeking the Green Party presidential nomination. His response was filed back in February 2011.