Actually, if you look at Utah's redistricting plans on its state legislature site, there's one plan that has the new district right in Salt Lake City, and Dems can make that competitive. But its first election in 2010, it'll be an at-large seat, which'll obviously favor Republicans, then in 2012 there'll probably be the incumbent effect, even if it is in Salt Lake City.
The Democrats already hold a seat in Utah. The new Salt Lake City district would become Matheson's district; it's more or less what his district looked like before the Republicans tried to gerrymander it away in 2002 by splitting Salt Lake City (and they failed). The Utah delegation after 2012 will be guaranteed to be 1 Democrat and 3 Republicans (whereas right now it's 1 Democrat and 2 Republicans).