Windows Live Messenger Wave 4, is introducing "full view" that doesn't replace traditional "compact view," rather, it's available in addition, and of course, you can switch between views at any time using view switch control. Messenger willn't only remember which view you prefer, but also whether you were looking at Social, MSN, or Xbox LIVE page in full view, and where you like each view to sit on your screen:
Full view – designed for social networking users, and allows you to access rich media and latest headlines and news from your social networks, MSN (see "MSN" next to "Social" at upper-left), and more. And soon will be adding social games from Xbox LIVE here as well.
Compact view – designed for IM purists, and shows more friends than in previous Messenger design, even when you choose to show user tiles. This's because we removed Wave 3 "social ticker" below the contact list.
Also, just drag the edge of compact view window horizontally to make it wider, to see multiple columns of contacts. When you maximize window on large monitor you can see five or more columns of friends!