This week i've spent a fair amount of time trying to figure out what we could potentially do to make reporting part of CiviCRM. A few joomla folks on the list have successfully used a Joomla component DBQ and were fairly happy with it. I did read a fair amount of it and took the next step of actually installing and playing around with it.
DBQ is quite nice, easy to install and works as expected. However, as Dan Robinson pointed out on the email list, it is not a reporting tool, but more a simpler way to execute queries and format them in some manner. A lot of "reporting" functionality is missing (in all fairness to DBQ, it does not claim to be a reporting tool either).