You aren't a developer, are you?
1) There are possible applications that can utilize dual-core. In this market, hardware leads software.
2) It is absolutely not a surprise that a dual-core iPhone would appear in 2011-12.
3) With more intensive parallable workloads, developers who are not multithreading are the ones that are short-sighted.
4) There is no such thing as a "dual-core applications". Software just creates threads and the OS manages the threads regardless of how many cores.