Make sure you are trying to "install" Memo.apk using a program like Root Explorer. It has to be put in /system/app with the correct permission.
Try clearing your Market Data/Cache in your Manage Applications > All
Or download the Memo.apk from an email sent to yourself or some website you can download from, save it to your external SD card, start the Terminal on the phone, "su" and "busybox cp /sdcard/Memo.apk /system/app"
I'm a FreeBSD geek after all....
Market Enabler from the Market worked perfect, tricked into thinking I'm on some US carrier & voila!