This year the Mint introduced a new version of Platinum Eagles with a burnished finish. The burnished coins can be distinguished easily since they have a "W" mint mark. The regular 1 Ounce 2006 Uncirculated Platinum Eagles had somewhat of a low mintage. As the Mint only struck 6,000 coins. Compare this to the mintage of over 133,000 coins struck for the 1 Ounce Platinum Eagle in 1998.
Therefore, the 2006 1 Ounce Platinum Eagle is one of the scarcer dates in the series. However, the coins don't tend to command a big premium compared to other dates in the series. Possibly due to the large amount of coins struck in the series and because of the Burnished and proof versions produced separately by the Mint.