According to the World Bank (i.e. the organisation chiefly responsible for the PPP calculations others use), Russias GDP at PPP in 2007 was already 6th, behind Germany, but ahead of the UK. In billion USD -Some quick facts on the growing Russian economy:
-10 years ago, Russian economy was a 200 billion economy, this year it has crossed $1.4 trillion mark.
-Today Russia is the 8th largest economy in the world in PPP, and by the end of the year it will overtake France to become the world's 6th largest.
-Last year foreign investment surged by a factor of 2.5 touching $100 billion.
-This year the Hydrocarbon exports will bring in more than $300 billion in earnings.
To put that into perspective in the 90's russia earned around $30 billion a year, roughly the same as the Soviet Union during the peak of the oil boom in the late 70's..
5. Germany - 2754
6. Russia - 2088
7. UK - 2081
8. France - 2054
9. Brazil - 1834
10. Italy - 1780
The margin of error is such that in reality, we don't know which of Russia, the UK & France is top.
Most of the growth from $200 billion, or whatever it was, 10 years ago to $1290 billion (World Bank, again) in 2007 has been due to appreciation in the exchange rate, not real growth. Don't confuse them.