Pomerol and St. Emilion are the two premier Bordeaux appellations on the other (right) side of the rivers from the city of Bordeaux and the glamour appellations of the Medoc; hence the term, "Right Bank."
The wines are quite different from those in the Medoc; the weather and soil vary significantly, and the primary grapes used in the region are the softer merlot and cabernet franc varieties, as opposed to the firm and tannic cabernet sauvignon of the Medoc. This makes for wines that are often much more attractive in youth--perhaps the reason why modern consumers have made the premier wines from these appellations some of the most coveted and sought-after in all of Bordeaux. However, this doesn't mean these wines lack the ability to age.
Pomerol, the only Bordeaux appellation to generally have a majority of merlot, is typically soft and lush, with a tremendous intensity of fruit concentration. The region itself and most of the estates therein are tiny; hence, the wines are in limited quantity and tend to be quite expensive.
St. Emilion, on the other hand, is a much larger appellation with a significant percentage of cabernet franc helping to comprise the blend. This too makes for softer, though still well structured wines, with distinctive cedary, herbaceous, mineral-accented flavors. Increased production quantities make them easier to find, and a number of bargains are to be had for the savvy consumer.
A final note: Vintage assessments in Bordeaux tend to be weighted to the Medoc, as opposed to the right bank. A given vintage will be declared excellent or poor with the supposition that this is universally true, which is not always the case. The recent vintages of 1996 and 1997 are a case in point. While 1996 saw excellent wines produced in the Medoc, it was not nearly as successful on the right bank. Conversely, while a number of Medoc 1997s were disastrous, the wines of the right bank look to be excellent. Thus, while certain vintages may have been overlooked due to a bias against wines from the Medoc, the right-bank versions may have been unjustly lumped into the same pot. By shopping with this in mind, it is more than possible to uncover a few hidden gems.