Mono
any (slight) pain to monkeys is inflicted under home office license

a Free (X11) re-impl. of parts of '.Net(tm)'
investment protection
a better development environment
a more powerful model

Definately in Gnome 14.7.3.2ac6
highly exciting
interesting background
replacing the duff windows APIs
multi-language, the many true ways
very rapid development
very rapid runtime
substantially bootstraps on Linux
http://www.go-mono.com

Amazing progress
ASP.Net, debugging, linear reg alloc, Gtk+, Qt, MonoLogo, ADO.Net