According to the National Association of Realtors, foreign clients -- not just investors, but future homeowners as well -- spent $41 billion in the United States in 2010. That does not include the additional $41 billion that "individuals with visas to stay for more than six months" spent during the same time period.
The report shows that though "foreign" buyers tended to buy "on the high end of the market" over the previous year ($315,000 vs. U.S.-buyers' $218,000), this year invernational investors are trending downward toward sales below $200,000.
The reason? U.S. property prices are just too good to resist, and overseas investors are taking advantage of the weakness of the U.S. dollar and pouring millions of their savings and investment pool into properties here. With the current exchange rates they can invest in assets at great values with tremendous upsides.
And, IMHO, the U.S. is one of the safest places to put your money. Away from unrest of northern Africa, various places in Europe, and the uncertainty of Japan in the wake of the tsunami and resulting nuclear plant issues.