I have a JB iPhone 3G running 3.1.2. I had previously installed a tethering hack, but never got around to testing it. I had a need for it recently, and attempted to tether, but no luck. I have the "Internet Tethering" option available in my config, and I was able to toggle that on without issue. However, when I went to connect to my phone via bluetooth, the connection failed. After that, the internet tethering option was no long visible in my settings. I tried to re-apply the tethering hack today using the instructions here: http://eagos.blogsite.org/eagos/Projects/Entries/2009/10/25_Enable_Tethering_on_iPhone_3.1.2.html. Attempting to do so, when I try and execute the file, I get the message: "Invalid CommCenter File. Make sure it's version 3.1.2 and that its not already patched." Any ideas what going on here?