Not every performance problem can be fixed with caching, but assuming you have done your due diligence and your application is already tuned and well designed, adding caching can dramatically improve response times and reduce the load on backend systems.
Next time you have performance and scalability issues with your application, consider the possibility of using caching (using IBM WXS or Oracle Coherence). Also consider the flexibility of the software caching vs. the ease of use and simplicity of the cache appliance. There is no one answer to every problem, but with IBM you have a choice. With Oracle you do not.
Read my full article comparing IBM and Oracle caching products: Data grids and caching – IBM or Oracle?