It's started. According to the latest Haarts figures reported in FindAProperty, average London house prices dropped -0.1% in July, but with huge regional variation. North London, for example, dropped -4.7%. The Olympic regeneration region, however, managed gains of up to 5% (Newham - developers have a nose for these things).

Olympic effect may reach Dagenham [July 28]
Olympics go nuclear [July 15]