Dave Watanabe's Inquisitor plugin for Safari has been the source of some controversy for affiliate linking shenanigans, and underwent some changes following the public outcry. None of that seems to have deterred Yahoo! from taking an interest in the search plugin. Yahoo! revealed today in a blog post that they would be acquiring the rights to Inquisitor.
The new version (which is a free download) removes affiliate links (completely, I assume) and updates the preferences interface. There is a reference in the Yahoo! post to a simplification of the process of selecting a search provider but I'm failing to remember what was complex about it in the previous version. Obviously, the top choice on the dropdown is now Yahoo!, but you can still choose to use Google and all of the other secondary search options appear to be intact.
I'll give Yahoo! credit for recognizing a beautiful interface and what many -- myself included -- agree is an extremely useful plugin. Whether Dave Watanabe's existing reputation will affect Yahoo! in any way is debatable, so I'm withholding speculation. Dave has made it clear that he remains an independent developer and is not joining the ranks of Yahoo!, remaining focused on his existing projects.