I've been a long time supporter of PreEmptive Solutions. They've done a great job of supporting .NET. As a Cleveland based company, they are in my territory as an evangelist.
Microsoft just released a huge press release on the new things that PreEmptive is doing - specifically, they are expanding well beyond obfuscation to anti-tampering, run time intelligence, licensing support for ISVs and much much more.
More on my blog at Microsoft and PreEmptive Solutions - new features for VS 2010