There's this vertical river-looking icon thing in my status bar? Nothing's claiming it in the notification window.
Crude recreation:
The third table in this page mentions "Vibrate": https://motorola-global-portal.custhelp.com/app/answers/detail/a_id/48504/~/droid-x---phone-status-%26-notifications
Even though the first table clearly depicts a different icon for the vibration mode, although with the same zigzag pattern.
The pattern is also the same as the icon I have for vibration mode on my SGS:
Cheers!
Looks like the icon for the "Silent" or "Vibrate" mode. These icons are different depending on the skin manufacturers/carriers put on their phone, but those wavy lines usually represent vibration.