My picks from ScienceDaily

Blind Humans Lacking Rods And Cones Retain Normal Responses To Non-visual Effects Of Light:

In addition to allowing us to see, the mammalian eye also detects light for a number of "non-visual" phenomena. A prime example of this is the timing of the sleep/wake cycle, which is synchronized by the effects of light on the circadian pacemaker in the hypothalamus. Researchers have identified two totally blind humans whose non-visual responses to light remain intact, suggesting that visual and non-visual responses to light are functionally distinct. Indeed, this separation was suggested by earlier studies in mice that demonstrated that circadian rhythms and other non-visual responses remain sensitive to light in the absence of rods and cones, the two photoreceptor types that are responsible for vision.

Related: Compared to your pet iguana, you are practically blind
Melanopsin

Semen Ingredient 'Drastically' Enhances HIV Infection:

A plentiful ingredient found in human semen drastically enhances the ability of the human immunodeficiency virus (HIV) to cause infection, according to a report in the December 14, 2007, issue of the journal Cell. The findings help to understand the sexual transmission of HIV and suggest a potential new target for preventing the spread of AIDS, the researchers said.

Mom's Personality Means Survival For Her Squirrel Pups:

A recent study indicates that mother squirrels have personalities, and they are essential for the growth rate and survival of her pups. Researchers at the Kluane Red Squirrel Project found that red squirrels have a range of personalities, from exploratory and aggressive to careful and passive. Both kinds of squirrels persist in the population because neither personality type offers an exclusive advantage for survival.

Andean Highlands In Chile Yield Ancient South American Armored Mammal Fossil:

A paleontological dig in Chile at an altitude of more than 14,000 feet in the Andes has yielded fossils of an 18-million-year-old armored mammal. It appears to be one of the most primitive members of a family of extinct mammals known as "glyptodonts," a group closely related to the modern-day armadillo.

Present-day Species Of Piranha Resulted From Marine Incursion Into Amazon Basin:

Piranhas inhabit exclusively the fresh waters of South America. Their geographical distribution extends from the Orinoco River basin (Venezuela) to the North, down to that of the Paraná (Argentina) to the South. Over this whole area, which also embraces the entire Amazon Basin, biologists have recorded 28 carnivorous species of these fish (2). In spite of the evolutionary success of this subfamily of fish, the mechanisms that generated the species richness of this group are still insufficiently known.