Yes you screwed your multiboot kernels!

Why the h..l did you overwrote your Nitdroid kernel?
Doing such mv (or cp) actions always very carefully, especially using autocompletion.

You may boot with keyboard out and press 0 for stock kernel.
Then rename again that
vmlinuz-2.6.28.10power46-XXX.NTD.XX
to
vmlinuz-2.6.28.10power46-wl1
This way you should get at least the power kernel up again.
For the nitdroid kernel you should check content of file
/etc/multiboot.d/xx-NIT........
You will find something like
ITEM_KERNEL=2.6.28.NIT.06
Go to ammyts NIT thread and download the kernel from e-yes or nitdroid website and put it under /boot/multiboot/vmlinuz-ZZZ, where ZZZ is what you have as ITEM_KERNEL.

BTW: There are already newer versions of power kernel and also bleeding edge drivers (only necessary for PK>=50) out.