It's interesting what you find in court documents sometimes. In response to recent legal concerns with the US Department of Justice regarding Vista's bundled desktop search tool. Microsoft has agreed to add the ability for users and OEMs to modify the default search in Vista. The most interesting tidbit is that the change will come in Service Pack 1, which will go into beta testing later this year, and be released mid 2008.
This is the first hint at Service Pack 1 since Vista's release, as Microsoft has been very tight-lipped about the details. With so many people holding off on upgrading to Vista until SP1 arrives, it's a bit of a surprise Microsoft hasn't been more forthcoming with information.