The U.S. Mint finally ditched the Sacagawea dollar and introduced the new "Presidential Series" dollar coins. Taking a page from the quarter series, they will release four coins a year with the portrait of a president, going in order starting with Washington:
Only four a year means it will take a while to get "current", but here's a key point: To be depicted on a coin, a president must have been dead for at least two years.
So Reagan will be good to go when they get to 40. What I am really hoping is that Carter is eligible when they get to 39.