DragonFly has two included compilers – GCC 4.4, and GCC 4.7. Traditionally, we switch from one compiler to the other as default, and then replace the old one with a newer release, and so on.
Until recently, dports built almost exclusively using GCC 4.4. John Marino’s switching to GCC 4.7, for a variety of reasons he lists in a recent post to users@. An interesting point that he raises: GCC 4.4 won’t necessarily be replaced with a newer GCC, but perhaps clang?