And apparently so was this mythical cruise module. They (wrongly) assumed they would be able to install an after-market cruise module in the smart, and back peddled quickly once they actually got a look under the lid.
I wound up ordering the MDC unit from SmartieParts and installing it myself. It was quick and easy (once I realized the 451s quirks), and works well. The stalk color is off a little when you hold the original next to it, but it's not at all noticeable once installed.
If you want details look for my other post in the forum about the install.