For a long time interning strings in HotSpot-VM would store the result in permanent generation. Since Java 7 this is no longer true. Interned strings are stored in the heap. As a result if you have an application where relied on intern() you may need to re-size your perm and your heap. Heap need to be larger Perm need to be smaller.
I understood that permanent generation is going to be removed from the HotSpot-VM in futures releases of Java.
Maybe this is the first step in this direction :)