Go back and analyze the Annual Report and the Notes to the Financial Statements @ 6-30-09, especially the Income Statement. Examine the several non recurring "exceptional" items like, e.g., the write-off of Ravensthorpe.
Then consider that BHP with a fiscal YE took the whole brunt of the recession in one reporting year. You will find the "static" P/E ratio is SOMEWHERE in the neighborhood of $16-17 in a real, meaningful sense of Income. You can't trust yahoo's figures, or hardly anyone else's. You have to do your own due diligence.
The P/E estimate is a snapshot in time using "Old" net income and O/S shares for with today's SP also. Who knows what the forward P/E really is??????
Also consider the current, and, debt to equity ratio's. Finally think about the on going growth of BHP. See what you think then. Just offering the way I see things FWIW.