I have a copy of Talkman (ordered from play-asia.com) and can tell you a few things about it.

First, the microphone is not comletely USB standard - it has two extra pins on either side of the USB connector, presumably for getting power from the (non-USB host?) PSP. So you would at least need an adapter of some kind in order to use a different USB microphone.

The SOCOM headset microphone does work with Talkman. I disconnected the USB mic, plugged in the headset, and the software still works. I didn't even have to restart the program - I just put the PSP to sleep, swapped mics, and brought it right back up.

The software itself is a bit "oversold" - it is really a phrasebook translator, so it simply recognizes key words (spoken) and then presents a list of canned phrases that it can speak in any of the four supported languages. You also have to change "scenes" to tell Talkman what kind of situation you are in (airport, hospital, general conversation, etc.) to help the software figure out what you are saying. It is rather slow - tons of animated parakeet stuff and lots of intro screens, etc. that I haven't figured out how to skip past when the software starts.

Oh, and I almost soiled myself when I saw that the outside of the box says that this software only works in Zone 3. But it worked just fine on my Zone 1 (USA/North America) PSP, as advertized by the vendor.

The program requires that you upgrade to 2.00 firmware.

Now if I can just figure out how to write homebrew apps that record audio from the microphone, I'll be happy...

EDIT:
Before anyone asks, I have not yet tested to see if the USB microphone works with SOCOM. Since SOCOM only supports voice in Infrastructure Network play mode, and since I've lost the documentation for my wireless router, I haven't had the time to mess around with it.