Should You Tell Bosses or Co-Workers if you have Chronic Illness?

Should you share news of a recent diagnosis of a chronic illness with your co-workers and bosses? What are the pros and cons of telling vs. not telling, short-term and long-term?

We'd love to hear your experience if you had to make this decision.

Here's a recent article in the New York Times about this subject:
http://www.nytimes.com/2008/02/21/fashion/21WORK.html?_r=1&ei=5088&en=0cf9e471a65a81c7&ex=1361336400&adxnnl=1&oref=slogin&partner=rssnyt&emc=rss&adxnnlx=1203627715-lyg1kh/d9kax5o6mJQYmyg