From now until Dec. 31, Medicare Part D is offering an "open-enrollment" period, meaning that seniors can change their prescription drug coverage to pick a new plan that better meets their needs.

Seniors should jump at this once-a-year opportunity. Instead of being forced into a one-size-fits-all plan run by the government, Part D participants can choose among a variety of private insurance plans, custom tailoring their coverage to their particular drug needs.

Since companies have to compete for the premium dollars of millions of Part D participants, they're delivering increasingly attractive offerings. Beneficiaries are seeing a broader selection of drugs, lower prices, and more generous benefits.

Indeed, the Centers for Medicare and Medicaid (CMS) estimates that the average monthly premium for standard Part D coverage in 2009 will be $28, only $3 higher than last year, and a whopping 37 percent lower than the $44.12 monthly premium projected for 2009 when Part D was launched.