RVL-CPU-30 is the third major hardware revision of the Wii. It has a smaller Broadway, but the main differences are found in the preburnt NAND. Some people refer to these as LU64+ Wiis, due to many Wiis with this revision starting with LU64 or higher. However, there are Wiis below LU64 with this revision as well.
They were once referred to as "unsoftmoddable," although this is due to a bug in the HackMii Installer that was easily fixed.