Here is a video by dennis96411, showing CM9 on the Exhibit II
What seems to work
HW accelerated display
T-Mobile Wifi-calling (works for most)
Camera (Stock Camera only, 3rd-Party apps mostly don't work)
Haptic keyboard feedback
What does not work (NO ETAs)
911 Emergency Calls
Torch app (check thread for alternatives)
CM9 for the Galaxy Exhibit is NOT vulnerable to USSD dialer exploits.
The content of text buffers sometimes disappear when touched (messages in: gmail,yahoo,fb). Wiping cache has fixed this for some. Long-press of back key and restarting app for others.
Facebook sync is not included in AOSP. 3rd-party apps are available in the market.
3g vs 4g
Cyanogen Mod views UMTS as 3g whereas the stock Exhibit II rom views it as 4g. Even though you see 3g on your status bar, your actual speed should be unchanged from stock.
Changing band preference
In dialer, enter Service Mode via
 WCDMA Band Preference
 GSM Band Preference
To force WCDMA only, tap option 2, on next screen tap option 6 - WCDMA All
To force GSM only, tap option 3, on next screen tap option 7 - GSM All
You can use the back button to verify your settings took effect. To exit, tap menu button, quit. This change does not survive a reboot. If you use this frequently, save it as a contact.
Wifi is working fine for almost everyone using CyanogenMod 9 Galaxy Exhibit build (and also for the Galaxy W). If you are one of the very few having difficulties, a possible fix has been posted that may help: WiFix Manager.
Installation requires a CWM-based recovery. Download/update Galaxy Exhibit Custom CWM Recovery here.
Updating CyanogenMod 9
Once you have a stable install you're happy with you can apply future updates w/o any wiping. If for some reason a wipe is required, I'll make that known.
Download CM9 Beta
Core2idiot's CM9 Nightlies
Google Apps gapps-ics-20120429-signed.zip .... Mirror
Copy the downloaded cm9 beta and gapps zip files to your internal or removable sdcard.
Back up your data.
Start Custom Recovery (cwm): Press & hold Vol-Up, then press & hold Power. Shortly after the plain white Samsung logo appears, release both buttons. Recovery should start after the color Samsung/T-Mobile Exhibit logo.
Home key = enter
Back key = back
VolUp/Dwn = highlight choice
If installing over a non-CM9 ROM you must do a ROMwipe before installing.
Select "Install zip from sdcard." Choose the cm9 beta zip from sdcard or external sdcard, depending on where you placed it. Highlight the cm9 beta zip file then press Home. Confirm the choice and installation will proceed. You may also install Google Apps (gapps) at this time. Gapps does not include all Google apps. Those not included are available from the market.
Please DO NOT PM me with support questions! Post them in this thread!