Not only is the Peter the Great and company on the way to Venezuela (hopefully, as long it doesn't break down), but Russia is continuing its military aid to Venezuela in the form of another arms contract. The newest contract with Venezuela will provide $1 billion dollars worth of arms--mostly APCs, anti-aircraft systems, and combat aircraft. There have been 12 arms contracts between the two countries since 2005 in the amount of almost $4.5 billion that provided fighter jets, tanks, and assault rifles.
Russia is also coming to the military aid of Nicaragua by helping to replenish its arsenal that was largely created by the Soviet Union in the midst of the Cold War. The arsenal once contained 2,000 missiles but half have been destroyed already. The US has put pressure on Nicaragua to continue dismantling its arsenal by promising aid for health care, claiming that the missiles could fall into the hands of terrorists. The arsenal was mostly furnished by the Soviets in the 1980s and is in disrepair because of lack of investment in equipment updates. The Soviets claim that they don't want to increase the arsenal, just fix the problems in the one that Nicaragua already has.
The re-election of Ortega in 2006 (who previously served as president from 1985-1990 and was backed by the USSR in the civil war against the Contra rebels backed by the US) has helped to strengthen ties with Russia. Nicaragua was also the only other country besides Russia to recognize the breakaway regions of South Ossetia and Abkhazia--a clear sign that they want to get on Russia's good side.
So what does this mean for the US? We of course aren't on the best of terms with Chavez and Nicaragua isn't our favorite south of the border neighbor either. We do maintain good relations with the majority of countries in Latin America and these two countries (along with Cuba of course) are a splinter in the side of the US. Yeah it kinda sucks that Russia is sending a decrepit missile cruiser to what we have referred to in the past as our backyard, and it sucks that Russia is taking such an interest in Latin America. But what can we do about it? At this point, I think we have our hands full with Iraq/Afghanistan and should worry about "rogue nations" that are capable of doing a great deal more damage that Nicaragua or Venezuela could. A lot has been said about Russia wanting to assert its own power to prove that it is a force to be reckoned with, and I think that this is a prime example of proving that it has gained back some of the power it lost since the Cold War by returning to its old stomping grounds in Nicaragua and supporting a friendly government in Venezuela. As long as these adventures are only "exercises" and aren't greatly increasing military capabilities to the point that it could be dangerous to the US, then I think that its in our best interest to monitor the situation but not to threaten or pressure with rhetoric because frankly, its not the biggest issue we have to deal with right now.