I have seen so many questions concerning the different types of yeast and what they may impart, I thought I would post an reference from http://winemaking.jackkeller.net/strains.asp
This is an excellent reference to keep handy and a special thanks to Jack Keller for compiling this extensive list. Below are just the Red Star listing but there are many, many other brands.
Red Star Active Dry Yeasts
Assmannshausen : Assmannshausen is a German yeast strain. Germany leads the world in yeast isolation and production. Assmannshausen is best suited for red wines. It intensifies the color and adds a spicy aroma. It first was only meant for Pinot Noir and Zinfandel, but now Cabernet Sauvignon takes advantage of this strain. The only drawback is its ineffectiveness in a high solid content.
Côte des Blancs : Formerly known as Epernay 2, this is another slow fermenting, very low foaming yeast tolerant of low temperatures. It tends to bring out floral and fruity qualities in wines and can be useful in both grape--especially fruity German style whites-- and non-grape wines--such as peach or raspberry--where a bouquet is especially desired. This yeast will not push alcohol production over 13% in a cool fermentation.
Epernay : Epernay is a Champagne yeast, meaning it was isolated in Champagne, France and is used in Champagne production. Epernay is used in bottle fermenting because it ferments slowly and is tolerant to cold temperatures with moderate foaming. It is also used for primary fermentations of still white wines.
Flor Sherry : Develops "flor" aerobically, but also useful for anaerobic fermentations of Port, Madeira, or other sweet styles.
Montrachet : Perhaps the most popular yeast used. It is available for both red and white wine fermentations and may be called Montrachet Red and Montrachet White. It works especially well in producing Chardonnay in barrel and stainless steel. It also tolerates sulfur dioxide well, but does not work well with high sugar levels (more than 23.5 percent). It is this ineffectiveness in high sugar levels that is most likely responsible for many stuck fermentations.
Pasteur Champagne : Champagne yeast is the second most common yeast strain used. It was isolated in Champagne, France and is technically a mixed-population culture. It is common in sparkling wine production because of its ability to induce fermentation quickly and because of its effectiveness in low temperatures and its tolerance of high alcohol conditions. These conditions are common in sparkling wine production.
Pasteur Red : Pasteur red is also called French red. Like Champagne, it is a mixed population strain. It was developed in Bordeaux, France. It is meant for red wines because it is tolerant to heat and sulfur dioxide and hardly ever causes stuck fermentation. The red wines it is usually used for are Cabernet Sauvignon, Merlot and Zinfandel.
Pasteur White : Pasteur white is also called French white. As the name suggests, it is used primarily for white wine fermentation because of its ability to ferment slowly and tolerate cold temperatures. It also gives off a noticeable yeasty aroma. Pasteur white foams considerably so it works better in stainless steel rather than wooden barrels.
Premier Curvee : Also known as Prise de Mousse, this is a Champagne yeast that is strong acting, low foaming and therefore qualified for barrel fermentations. It imparts a strong yeasty aroma and is useful for secondary fermentation in both still and sparkling wine production. Good for reds and whites alike and for restarting stuck or sluggish fermentations.
Steinberg : A strain developed in Germany. Like Pasteur white, Steinberg is used for white wine fermentation because it yields a lengthy fermentation process. It even tolerates the cold better than Pasteur white. Johannesburg Riesling, Gewürztraminer, Chenin Blanc and Muscat all use this strain. It gives off a tropical fruit aroma and is best used in stainless steel fermenting.