[ROM-alpha] CyanogenMod 10 (Android 4.1.2) 
Alpha preview, not intended for daily use!
Nightly builds: http://skrilax.droid-developers.org/...y/umts_sholes/
OpenRecovery 2ndbootOR: http://code.google.com/p/cyanogenmod...ootOR_v1_1.zip
JellyBean is very big, therefore ext partition on SD card is required - part of the system and most of the gapps is installed there.
You can find instructions on how to resize fat and create ext partition directly in OpenRecovery in this very fine guide by pontomedon:
Full guide from stock Motorola Android to CyanogenMod 7 for Milestone
Please use 2ndboot based OpenRecovery for installation to avoid sdcard write errors.
The CM10 builds are using 2ndboot to run custom kernel.
Thanks to Skrilax_CZ, the issue of low performance before the first device suspend has been resolved (L2 cache remained disabled before).
The bad GPU performance on CPU clock bellow 600MHz
is currently successfully worked around by temporary insmod of older pvr driver
during boot, so it's not an issue anymore (from the user perspective)
has been properly fixed by Skrilax_CZ.
Wifi tethering should work since 20121028 nightly.
Other known issues:
- video recording is not working very well currently
HW acceleration increases the application's RAM demands. You can use the included HWA Settings app to disable it per app.
Remember that JellyBean is designed for devices with much bigger RAM than Milestone has. Don't expect miracles