Yes, Tenchu 4 is coming to the PSP. Japan gets it on February 12, but Tenchu 4 on the PSP isn’t exactly the same experience you get with the Wii. Anyone that picks up the PSP version has to give up motion control in exchange for portability. Some gamers might consider that a positive, but the graphics are also taking a noticeable hit. Instead of shadowy figures the PSP version gives you solid color models when you use your ninja vision.
The Wii version has plenty of quick time events which require motion control. It appears that Tenchu 4 for the PSP handles these with pop up commands on the bottom of the screen.
One element you won’t be missing out on in the PSP version are crotch kicks.
Mix and place lethal poison to incapacitate your targets.
Use smoke bombs to confuse your enemies while you run through them.
This tool lets Rikimaru breathe underwater.
For a frame of reference here is what Tenchu 4 looks like on Wii.
Images courtesy of From Software.