Stem cell biology for the general public is fairly obscure and the subject overwhelming for many reasons: It is the fact that stem cell autonomously divide and create cellular progeny that sometimes is again a stem cell, sometimes a cell matured along its predetermined cell fate. In the shop there are stem cells for any major tissue, at least for mice, and it is difficult to stay informed.
Therefore the review by Clevers, Lo and Nusse (Utrecht and Stanford) on An integral program for tissue renewal and regeneration: Wnt signaling and stem cell control in Science this week is a good primer for those who are not part of the business. It gives you very basic knowledge on Wnt, its role in stem cell biology, its regulation, and finally the role of Wnt in assymmetric cell division. This is supported by very clear figures which I highly recommend.
Do not miss this paper!