Wikinews is too dynamic and has it's own set of problems to merge easily.
It could be done though if given it's own namespace, and Wikipedia would definitely benefit.
+1
In the topic area I work there are a lot of contributors writing content that is vastly more suited to Wikinews. A News: namespace would be really interesting; but of course it's unfair to step on the toes of a fledgling project. But perhaps in hindsight it should have been launched as a namespace.
Tom