exchange rate - tax return and 8938/FATCA

I want to make sure I'm getting this right.  The 2011 unofficial average for the pound is $1.54 - according to IRS and embassy, so you can use that in figuring your tax return. For 8938/FATCA and for FBAR, you use the Treasury figure for the exchange rate on 31 December 2011. That is $1.56. Different rates for different filings. Is this correct?

Hi Marty,

The unofficial rate for 1040 is 1.54. The Treasury rate at 31/12/2011 is 0.6370 (1.5699) for FBAR and 8938.

many thanks.