No alternatives to Market on the US version X10...

I thought I try SlideMe, an Android community supported alternative Market app.

http://slideme.org/
 
It installs (through the debug interface using adb install sam2.apk)

But once you try to use it, i.e., download and install an app, the US X10a tells you that the feature to install non Market apps was disabled on the device.

Thanks Sony & Ericsson!