Do you have a name with non-ASCII characters?
There is a bug regarding developer certificates with non-ASCII characters in them.
I've filed a bug report, to Appcelerator's Lighthouse site:
My name has a character with umlaut (ö) which prevents prereq.py from doing what it should. Titanium only says "Loading..." in the SDK version select box.
The patch attached to the page, which changes json parser into simplejson, helps the python script to pass. I run it in console and get the expected output:
'{"wwdr": true,"ipad": false,"sdks": ["3.1","3.1.2","3.1.3"],"iphone_dev_name": ["Björn Söderqvist (XXXXXXXXXX)"],"iphone_dist_message": "Missing iPhone Distribution Certificate","wwdr_message": null,"itunes_message": null,"itunes": true,"iphone_dev_message": null,"iphone_dev": true,"iphone_dist": false,"itunes_version": "9.0.3"}'
Titanium app still reads the output wrong though.
It works if I copy-paste the console output of patched prereq.py like so:
(line 877 of packaging.js)
var d = '{"wwdr": true,"ipad": false,"sdks": ["3.1","3.1.2","3.1.3"],"iphone_dev_name": ["Björn Söderqvist (XXXXXXXXXX)"],"iphone_dist_message": "Missing iPhone Distribution Certificate","wwdr_message": null,"itunes_message": null,"itunes": true,"iphone_dev_message": null,"iphone_dev": true,"iphone_dist": false,"itunes_version": "9.0.3"}'
https://appcelerator.lighthouseapp.com/projects/32238/tickets/646-iphone-sdk-problem-with-non-ascii-characters-in-development-certificate
Unfortunately, the link I refer to in the post does not work anymore. The suggested patch was to do the following to prereq.py:
Line 8
#import json, run, tempfile, codecs
import poorjson, run, tempfile, codecs
Line 139 (replace last line of check_for_package() with this)
print poorjson.PoorJSON().dump(props)
Let me know if you need more specific information.