It's great to see the HN community responding positively to news about .NET/Mono and related tech. I've been working with C#/.NET since 2008 and always felt it's a vastly superior platform to Java in every way. It's a shame it is taking so long for the wider tech community to realise this.
1. The compiler checks for exceptions being thrown and and makes you write a catch.
2. Anonymous inner classes.I prefer even handlers, but would still like this feature.
I think c# does a good job of always adding features that make it easier to write code.