It seems clear now (correct me if I'm mistaken) that Nazi intentions regarding the pact were to use it to stall for time, and renege on it when they felt ready to start the war in the East. But what do we know about what Stalin and the Soviets' intentions were? Did they intend to honor the pact for the foreseeable future, or were they intending to stall for time and renege on it as well?
I've read through the Wikipedia article on the pact, which has detailed information on the political maneuverings leading up to the pact, but seems to say little on the Soviets' long-term intentions regarding the plan.
Up until 1938, Stalin's primary foreign policy in regards to fascism, and Nazi Germany, stemmed from his idea of a "Popular Front against Fascism". This was intended to be a front by all democracies, and communist nations against the (what Stalin perceived to be) larger threat that was fascism in Europe. This can be seen in Stalin's intervention in the Spanish Civil war (he sent a number of tanks, planes and military advisors which aided the Republicans from 1936-38).
In 1938, when Hitler demanded that Czechoslovakia cede the Sudetenland to Germany, Stalin was prepared to support the Czech armed forces in the defence of the Sudetenland. However, after the Munich Agreement, the Sudetenland was ceded to Germany, and in 1939, a large portion of Czechoslovakia was then invaded and taken by Germany. It's widely considered that this is the turning point in Stalin's foreign policy in relation to Germany and fascism.
While prepared to fight, the USSR was not militarily capable of a war with Nazi Germany in 1939. Due to the very recent purges of his military, Stalin had virtually no capable officer corps. His industrialisation program by the five-year plans was on schedule, but not to a degree where the USSR could confidently defeat the Nazi War machine. So, the main aim of the Molotov-Ribbentrop Pact was for the Soviet Union to gain further time, to prepare for the inevitable war with Germany. At no point did Stalin expect peace with Germany to be a lasting thing. There is no documentation specifically stating when/if Stalin intended to attack nazi-Germany that I'm aware of.