Based on USBKeyboardMouse example. I added USB String Descriptor so mbed reports itself to host not only with VID & PID but also with name of manufacturer, product name, serial number, configuration number and interface name. These can be changed to matching Yours in USBhid.cpp file on lines 88 - 122.

Dependencies:   mbed

Revision:
0:f97b1f255167
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Sep 08 15:01:33 2011 +0000
@@ -0,0 +1,17 @@
+#include "mbed.h"
+#include "USBMouse.h"
+#include "USBKeyboard.h"
+
+DigitalOut led(LED1);
+USBMouse mouse;
+USBKeyboard keyboard;
+
+int main() {
+    while(1) {
+        mouse.move(18, 10);     //moves the mouse down and to the left
+        keyboard.sendKeys("mbed");     //sends the word "foo" through the keyboard
+
+        led = !led;     //cycles the LED on/off
+        wait(2);        //waits 2 seconds, then repeats
+    }
+}