Updated 06/11/2006: If you are trying to locate the Netron Project see my post "What happened to the Netron Project?"
Francois has done it again – he’s proved that he’s one of the best open source .NET developers out there, by releasing Lithium – a Tree Diagramming Control – building upon many of the ideas and implementations of Netron.
I was lucky enough to be a participant of the limited beta programme and have been playing around with Lithium for a few weeks now – the uses are endless.
I’ve already re-written the library using interfaces rather than using base classes – which makes developing new shapes a lot easier – it also cleans up various bits of the architecture and simplified de/serialisation a little which makes adding new shapes much easier. I’ve also started porting Lithium over to .NET 2.0 to make use of Generics, Anonymous Methods and various other goodies. I’ve also been working on various sample applications which use Lithium – the possibilities really excite me – I just wish I had more time to develop these ideas!
Hopefully Francois will integrate some of my “addition” to a future release (below is a Visual Studio 2005 Class Diagram of the Lithium Control).

If you look on the Netron Project home page you can see that Francois has very ambitious plans for the summer - he's releasing a whole slew of new controls:
I can't wait to see what else he's going to come up with over the comming months.