Also you can try to edit an adb config file .android/adb_usb.ini and add a line 04e8 after the header. Restart adb required for changes to take effect.
I have a Fascinate as well, and had to change the phone's USB communication mode from MODEM to PDA. Use:
enter **USBUI (**87284)
to change both USB and UART to PDA mode. I also had to disconnect and reconnect the USB cable. Once Windows re-recognized the device again, "adb devices" started returning my device.
BTW if you use CDMA workshop or the equivalent, you will need to switch the setting back to MODEM.
I have a Samsung Galaxy and I had the same issue as you. Here's how to fix it:
In device manager on your Windows PC, even though it might say the USB drivers are installed correctly, there may exist corruption.
I went into device manager and uninstalled SAMSUNG Android USB Composite Device and made sure to check the box 'delete driver software'. Now the device will have an exclamation mark etc. I right clicked and installed the driver again (refresh copy). This finally made adb acknowledge my phone as an emulator.
As others noted, for Nexus 4, you can also try this fix.
I have a ZTE Crescent phone (Orange San Francisco II).
When I connect the phone to the USB a disk shows up in OS X named 'ZTE_USB_Driver'.
Running adb devices displays no connected devices. But after I eject the 'ZTE_USB_Driver' disk from OS X, and run adb devices again the phone shows up as connected.
I just spent half a day trying to connect my various Android devices to my MacBook Pro (running 10.8.2). It turns out to have been a Micro USB cable problem. I have many Micro USB cables, but only the one that came packaged with my Galaxy Nexus works to connect the phones to my computer. I don't know if this is due to damage, or some proprietary manufacturing, but please remember to try connecting the phone with the cable that was packaged with it.