We've been using Poco in Appcelerator Titanium (desktop version) now for about 8-9 months and very satisfied.
Appcelerator Titanium gives web developers a platform to build cross platform applications using web technologies. We use Poco as one of our core libraries.
Appcelerator Titanium is open source and source is located at http://github.com/appcelerator/titanium_desktop
You can find out more information or download at http://www.appcelerator.com
Thanks to the Poco team for such a great product!