How long will it be before we can reliably coax embryonic stem cells in the lab to develop into gametes (sperm and eggs) without serious abnormalities? This capability would be useful for embryo selection, both to produce more eggs and thus embryos to select among, and to enable iterative embryo selection, a technique which parents could use to create "designer babies" with traits that range from reduced risk of particular diseases to abilities that contribute to success in science.

• Claim: "Based on published data and theoretical considerations, it is probable that human eggs and sperm will be derived partly or entirely in vitro from pluripotent stem cells. The pace of scientific progress is difficult to predict. Unanticipated findings can either accelerate or slow the pace of progress. With this caveat, the derivation of human eggs and sperm in vitro from pluripotent stem cells, in whole or at least in part, is anticipated within 5 to 15 years." (2008)
  Implication: The technology is likely to arrive between 2013 and 2023.
  Source: The Hinxton Group. "Consensus Statement: Science, Ethics and Policy "Challenges of Pluripotent Stem Cell-Derived Gametes." Press release.11 Apr. 2008. 9 Aug. 2008 <http://www.hinxtongroup.org/consensus_hg08_final.pdf>. 

• Claim: "Based upon the expression of several key genes found in oocytes, the team concluded that mouse embryonic stem cells were capable of being cultured in a laboratory to develop into gametes."
  Implication: Artificial mouse gametes have already been produced, since at least 2002. Artificial gametes in humans probably aren't far off.
  Source: "Development of Gametes from Embryonic Stem Cells." Medical News Today. 19 Oct. 2005. Retrieved 9 Aug. 2008. <http://www.medicalnewstoday.com/articles/32262.php>. 

• Claim: "So far, artificial sperm has only been used to create pregnancies in mice: the resulting offspring did not survive long, succumbing to genetic abnormalities."
  Implication: If artificial gametes techniques are to be applied to humans, they will need to be refined to avoid damage to the resulting embryos.
  Source: "'Limit' to lab egg and sperm use." BBC News Online. 14 April 2008. <http://news.bbc.co.uk/2/hi/health/7346535.stm>

• Claim: "Scientists in the UK have proved that human embryonic stem cells can develop in the laboratory into the early forms of cells that eventually become eggs or sperm. However, Mr. Aflatoonian stressed that there was still a lot of work to be done before the promise of these early results could be translated into reality." (2005)
  Implication: Artificial human gametes are on the way, but not immediately.
  Source: Mason, Emma. "Human embryonic stem cells have the potential to develop into eggs and sperm in the laboratory." EurekAlert. 19 June 2005. <http://www.eurekalert.org/pub_releases/2005-06/esfh-hes061705.php>.