Is telomere length a reliable measure of health/lifespan?
I disagree with Ctina.  So many factors go into determining loss rate, activity of telomerase, gene conversion or unequal exchange at chromosome ends, etc to ever say that length is a function of age.  There is far more variation between individuals and between cells within an individual than aging ever shows.  Here is one study:

Das B, Saini D, Seshadri M. Telomere length in human adults and high level natural background radiation. PLoS One. 2009 Dec 23;4(12):e8440.

however I've seen similar studies published elsewhere.  Telomere length as diagnostic for age is very poor at best.  Here's an article that gives a formula, but acknowledges the R2 is 0.04, which is useless: http://preview.ncbi.nlm.nih.gov/pubmed/18378481