Stackless python stopped mod_python/apache from working
When you install a new version of Python (whether stackless or not) you also need to reinstall all of the third party modules you need -- either from sources, which you say you don't want to do, or from packages built for the new version of Python you've just installed. 
So, check the repository from which you installed Python 2.6.2 with aptitude: does it also have versions for that specific Python of mod_python, mysqldb, django, and any other third party stuff you may need?  There really is no "silver bullet" for package management and I know of no "sumo distribution" of Python bundling all the packages you could ever possibly need (if there were, it would have to be many 10s of GB;-).
I installed stackless pyton 2.6.2 after reading several sites that said its fully compatible with vanilla python. After installing i found that my django applications do not work any more.
I did reinstall django (1.1) again and now im kind of lost. The error that i get is 500:
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, webmaster@localhost and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Apache/2.2.11 (Ubuntu) DAV/2 PHP/5.2.6-3ubuntu4.1 with Suhosin-Patch mod_python/3.3.1 Python/2.6.2 mod_ruby/1.2.6 Ruby/1.8.7(2008-08-11) mod_ssl/2.2.11 OpenSSL/0.9.8g Server at 127.0.0.1 Port 80
What else, could or should i do?
Edit: From 1st comment i understand that the problem is not in django but mod_python & apache? so i edited my question title.
Edit2: I think something is wrong with some paths setup. I tried going from mod_python to mod_wsgi, managed to finally set it up correctly only to get next error:
[Sun Aug 16 12:38:22 2009] [error] [client 127.0.0.1]     raise ImproperlyConfigured("Error loading MySQLdb module: %s" % e)
[Sun Aug 16 12:38:22 2009] [error] [client 127.0.0.1] ImproperlyConfigured: Error loading MySQLdb module: No module named MySQLdb
Alan