Which brings us to your second question: What is the 3.3v standby? The wii actually has TWO 3.3v voltage lines.
The 3.3v line powers the GPU, flash memory, gamecube controllers, sd cards and several other components that are used only while the console is on.
The 3.3v standby powers the MX chip, bluetooth module, and other components that still run while the console is off. This allowed the console to be booted wirelessly using the wii remote.
Why have you never heard of this before? For portablizing, it isn't really relevant. We don't need standby functionality and just power everything off of a single 3.3v regulator. The only thing you need to be concerned about is making sure you connect the two sections.