Kayak, a new travel search meta site that I've mentioned several times on the SEW Blog, has just launched a beta version.
Kayak, simultaneously searches more than 60 site for air fares, hotels, and car rental pricing info.
One feature I like about Kayak is how simple narrowing a results set it. Several refinements can be made by simply by moving 'sliders' (change flight times, price range, etc.)
This is very similar to the Smart Sort technology that Yahoo makes available for several product categories. Here, you can use sliders to help select the best product based on what's more or less important to you.
Kayak offers both HTML and Flash search interfaces.
Former executives from Orbitz, Travelocity, and Intuit are all part of the Kayak management team.
Here's the Kayak beta release announcement.
Also, Pamela Parker takes a look at Kayak in the Clickz article: Travel Vets Launch Beta of 'Google for Travel'.