On Fedora, I was having issues getting my T-Mobile G2X to connect in developer mode.
For sure, I was setting Settings-Applications-USBdebugging to Checked. And when plugging in the device, the SD card (and/or) internal memory space was showing up on the desktop (and the output in /var/log/messages looked equivalent to that from my working G1) [...]

These direct steps (using the openjdk, not the Sun one) are confirmed to work…
Below, the following are our (typical) values :

MY_ANDROID_SDK : /path-to-android-sdk-installation-root/android-sdk-linux_86
MY_TITANIUM_DEVELOPER_DIR : /path-to-titanium-developer-installation-root/Titanium Developer-1.2.1
MY_TITANIUM_FILES_DIR : /path-to-my-home-directory/.titanium
MY_TITANIUM_SDK : /any-suitable-directory/

Note that MY_TITANIUM_FILES_DIR is the default created/used by the Titanium Developer program, which one runs from MY_TITANIUM_DEVELOPER_DIR using ./Titanium Developer
Check that the build tools are [...]

Requirement : Get the 32-bit Android SDK to work on a 64-bit Fedora machine (Fedora 11 tested below), using the standard openjdk rather than Sun Java. No eclipse required, since development will be done using Titanium.
32-bit libraries are required. To clear out existing libraries (only if you know you haven’t got anything else [...]

Create /etc/udev/rules.d/91-android.rules with the contents :

SUBSYSTEM=="usb", ATTRS{idVendor}=="0bb4", SYMLINK+="android_adb", MODE="0666", OWNER="rmbsanal"

Then

/etc/init.d/udev-post reload

and re-plug in your Android phone. That’s it.