IMHO, Epic aren't promoting UT3 for the sake of profits - the engine is harvesting enough wealth in that regard, and Gears / Gears 2 are also very successful. They're promoting it in order to get more players involved.
Well first, "what's the difference?" is one question I'd pose—the low shelf price effectively means low cost to Midway/Epic for offering free weekends.
So I'm guessing their trying to get more interest into UT3, so maybe that means a UT4 or 5 or 2011 or something.
This man speaks obvious truth.
People declare it dead because it's not getting it's full power. Ever.
... UT3's reign lasts at least until the next UT comes out...
define "reign"...
I think it's a great idea! You get more people involved and after the free weekend, some people may actually go out and buy it. Also, the people that already have a computer that can run UT3 and haven't tried it yet get a taste. This also might get people interested in the mods and stuff.