Here is a great website that I found the other day, that has some very good info. It is the National Strength and Conditioning Association.
http://www.nsca-lift.org/default.asp
Take a look at their back issues of their magazine,and take a look at the one about nutrition.
http://www.nsca-lift.org/Perform/backissues.asp . I like these because they are in .pdf format so you can save them and print them out if you desire.
Lunchbox7 is correct, many people eat way too much protein in their diet when trying to bulk up. Your body has to work harder to convert protein to energy than it does carbohydrates and it is not nearly as clean a fuel source. It produces more waste and is harder on the kidneys, liver, and urinary tract (see article on nutrition).
So, just be careful on the protein. Adding 20-25 mg more to your diet can definitely help you, especially if you don't eat many meats in your normal diet. Also, along with the shakes, you might try some of the meal replacement bars. Make sure to check these out though.. there are tons of them on the market and some are very high in Fat, Calories, or Carbs, or any of the above, or all of the above. Personally, I try to find ones relatively low in carbs, have a moderate amount of fat (hey, it's better than eating a candy bar), and are low in sodium and cholesterol if possible,and most importantly taste somewhat worth like something you'd actually eat.