Um, pretty interesting. I deem it another difference between AmE and BrE.
I was listening to Sean Hannity show online and he called Easter Sunday 2010 to fall on 'next Sunday, not this Sunday'. However, I have checked Easter this year falls on the first Sunday in April. Thru what he said, I was at a loss as to the definition of 'this Sunday' and 'next Sunday', and that is why I posted this thread.
As a non-native speaker, I think I would be better off to say 'upcoming Sunday' to refer to March 21 and 'Sunday after next' for March 28.