OWC is retiring
For years OWC (stands for Office Web Components) has been serving to web developers as a power graphic engine. Free for non-interactive scenarios, it provides Excel-style charts.
Now it is on the way out. OWC is being deprecated and will not receive any functionality updates (http://blogs.msdn.com/excel/archive/2006/07/17/668544.aspx). Instead Microsoft will be offering a technology called Excel Services which is a part of Microsoft Office SharePoint Server 2007. It has been designed to scale and perform on a server. But it as not going to be a replacement for OWC from the functionality perspective and it is not free anymore.
Although technically nothing stop me from continuing using OWC in new projects and recommend it to others, I don't feel comfortable relying on a deprecated technology. Looks like I will rather need to shop for a third party component.