After reading the previous thread on PORT, I thought I'd add a few comments on Port, and its ageing based on the generally available three styles of port.
These comments are related to true PORTs (ie. portugal) as opposed to many fortified wines that may or may not represent themselves as port (ie. Port-style)
1. Tawny Port... Is aged in casks where oxidative aging occurs resulting in a non-tannic style (ideal for sherry drinkers looking for less grape and more wood). This might be the best port for those who like whiskeys, while the following two styles would be best for those who prefer wines.
2. Late bottle... the port is aged for 4-6 years and is often labelled with vintage year and aging data. Typically this port is bottled at it's prime (ie. released to market when the bottler deems the product is READY TO DRINK). This style of port is typically not going to improve with age, in fact will indeed loose some of it's appeal. Generally, if there is a stopper cork, the merchant deems the product ready to drink. If it is a driven cork, one might assume some improvement with moderate aging. These ports are the type that you can open and sip at. Best kept in the refridgerator, they can be quickly brought to room temperature in a microwave. These are the styles of port you will want to buy now to enjoy now.
3. Vintage Port... This is bottled early (30 months maximum aging) and is DEFINITELY designed to age in the bottle. While yeast is killed by the addition of spirits, there is still reactive aging. The tannins (protiens) will bind and drop out of the port, and the fruit will mature. Quality vintage ports will typically age 15-25 years, and some will then remain at their peak for another 15-25 years (but who can wait for 50 years). These ports, once aged and subsequently opened, are really designed to be drunk up in one sitting (ie. they will quickly deteriorate). These are the styles of port you will want to buy now and put down for future celebrations.