Question: I am looking out for a good open source Reporting tool/framework for windows based application (WPF). 

The database I am using is sql server 2005.

The typical reports format which I am interested is for e.g. Trial balance, balance sheet, etc (typical banking / finance reporting application).

There should be good support for charting as well.

If anyone has any experience with reporting for WPF application, your inputs will be highly appreciated.

Answer: 
Since this may form part of the answer, I thought of putting this in the answer section.
I just found this series of article
[WPF multipage reports](https://web.archive.org/web/20121214141444/http://janrep.blog.codeplant.net/post/WPF-Multipage-Reports-Part-I.aspx) **(note: original link dead, replaced with Wayback Machine link)**. 

Thought of putting this here as this may benefit some other learner. This article walks through creating a reporting framework for LOB Apps.

As the saying goes "A Bird in the hand is worth two in the Bush", I will have a deep look at this until something else comes up with something better :)
As open source, this doesn't exist, at least not yet. 
It probably doesn't exist commerical offering either. The WPF component market is just getting started.