Snow Leopard has just been put onto the UK Apple Store and is expected to ship on Friday the 28th. It's £25 for us UK people.
http://store.apple.com/uk/product/MAC_OS_X_SNGL?mco=NzgxMDc3NA
http://store.apple.com/uk/product/MAC_OS_X_SNGL?mco=NzgxMDc3NA