I know that PDAnet and other methods of USB tethering are widely discussed on the forums, and that works great for Windows and Mac ... here is a method that works for Linux and does not require root on your driod:
Linux + GNU = Humans Enabled: How to Tether your Verizon Droid (as an Internet modem) to Ubuntu GNU/Linux 9.10
This method works on Ubuntu 9.10 and with a couple modifications, works on CentOS 5.
The CentOS 5 mods are listed in the comments, here are some more details for CentOS:
1. You need to setup the RPMFORGE repo for CentOS 5 to install openvpn:
AdditionalResources/Repositories - CentOS Wiki
Then install openvpn with the command:
yum install openvpn
2. You need to edit the AziLink.ovpn file and add a # to the line socket-flags TCP_NODELAY to remark it out. So it becomes:
3. You must set up sudo to work with the user who is going to run the sudo commands, and you must use the NOPASSWD option for sudo ... or run the connect script as root.
TipsAndTricks/BecomingRoot - CentOS Wiki
4. Change the openvpn command in his scripts to /sbin/openvpn as sbin is not in a normal user's path.
5. In his step 6 he has the command sudo restart udev instead use this command to restart udev:
I am not sure of other versions of Linux where this works, but it should work on Fedora and most other versions of Linux that use similar versions of udev. In the comments, Linux Mint and OpenSUSE 11.1 are mentioned as working.