There has been great speculation of late about the details of the much-anticipated US invasion of Iran. Proposed war-plans and armchair generals alike have honed in on the key role that Azerbaijan will play--as a jumping off point and key logistics node for the operation. For that reason, it seems highly significant that STRATFOR is now reporting that US military advance teams have arrived in country, and are preparing facilities for larger US deployments later this year (subscription required for link).
Stratfor is a private intelligence service, and has proven themselves to be the most reliable source of RUMINT, accurately predicting most major world events of the past decade.
Specifically, Azerbaijan holds the former-Soviet airbases of Kurdamir, Nasosnyy and Gyulakh. These were forward deployment locations for the USSR's IL-76 'Candid' transports and TU-22M 'Backfire' bomber, and therefore will have at least the skeleton of the infrastructure required for a major US deployment and airlift operations. STRATFOR forecasts the creation of "lily pad" bases, from which US forces will be able to stage men and materiel for an invasion of Iran. Access to Azerbaijan opens the critical Caspian route to Tehran, reducing the arduous march over mountainous terrain that would be required to reach the capital from Iraq.
As the situation in Iraq promises to be stabilizing--even if stabilizing at a significant level of violence--US planners may well be looking to the next step in their grand strategy. And Azerbaijan is a wise next step (from their perspective)... access to Tehran, and an excuse to garrison troops in the oil-rich Baku region to boot!