The Microsoft .NET Framework Developer Center has posted a .NET Framework 1.0 SP3 and 1.1 SP1 Technical Preview that includes downloadable versions of upcoming service packs for both the .NET Framework 1.0 and 1.1. It should go without saying, but because this is a technical preview, it is unsupported and intended for testing purposes only (in other words, don't install it in a production environment).

For a look at the fixes that are available with each service pack, see the lists for version 1.0 and version 1.1. Additionally, 9 newsgroups have been created to report any bugs or problems that you encounter.