With a little sleuthing, Gary Price discovered what appears to be experimental prototypes for the new MSN Search.
Most curious is the use of sliders to modify the search results. Google Personalized Search has a similar slider feature, but I thought it was widely viewed as ineffective. Interesting to see MSN experimenting with it.
Update: Andrew Goodman thinks sliders could be big, giving users the ability to customize relevance rank as they wish.
I suspect sliders would be of interest only to power users, the kind of people who already use advanced search all the time. Most users want search to "just work". This kind of control is just a novelty, not something most would actually bother to use.
This discussion reminds me a bit of the debate between Udi Manber and Louis Monier at Web 2.0 on whether users want more powerful tools or just want the right thing to happen.