This was just posted few min ago on the web as a official Apple PR /AP.
"Steve Jobs has hormone imbalance, will remain CEO"

http://news.yahoo.com/s/ap/20090105/ap_on_bi_ge/apple_jobs_health
NEW YORK – Apple Inc. founder and Chief Executive Steve Jobs, looking to quell rumors about his health, said Monday his doctors have discovered a hormonal imbalance that has been causing his weight loss.
Jobs, 54, said he will undergo ......