You are right, recessions usually are measured with a drop in real GDP. However during the 4th quarter of 2007 we had about a 4 percent growth in real GDP
http://www.bea.gov/newsreleases/national/gdp/gdpnewsrelease.htm
Unemployment high? not at all, in February 2008, only 4.8% of the country was unemployed.
http://www.bls.gov/
5 percent unemployment is nothing, you have to realize that this includes people who are frictionaly umeployed, or moving between jobs, just getting out of school, etc... That figure also includes structural unemployment which is the type of unemployment that exists when technology or consumer demand change and cause an industry to go under. One example of this would be the cassete tape industry in the 90s when CDs took over.
The value of our currency dropping isn't neccasarily dropping, as long as it doesn't drop to much it could help our economy rebound.
GDP is equal to C+G+I+X where c=consumption, g=government spending, i= gross investment, and x= net export (export-import)
So as the American dollar gets weaker relative to other currencies two things will happen. 1) We will begin exporting more items. If countries can import goods from the US due to our weaker dollar they will. This will cause us to become even closer to full employment and bring more factories back to the US. 2)We will import less items. This seems obvious if we are exporting more. If we are importing less then the will in fact hurt the economies of countries with stronger GDPs because there not exports will go down.
You see when you combine the effects of #1 and #2 our net exports will go up and boost our GDP