Completely agree with refurb. Guys, you have been admitted to some very top schools (at least unplugged, judging from your profile), and MBA does require some degree of adult thinking. Some extra thoughts:
So, here is the situation. It is your short and long-term benefits vs. risks.
Short-term benefits: making some extra money during your stay with a company (in case you are absolutely confident you will be asked to leave shortly after you inform about leaving at the end of Summer)
Long-term benefits: none really. This will not help your career in any way at all.
Risks:1. Leaving on bad terms. No need to elaborate on that much.
2. Depending on the nature of your work / urgency of ongoing assignments, and how badly your
enexpected leave will hurt the company, I would not be surprised if your boss decides to write a letter to the b-school informing them about this.
Remember, since you were accepted, you are perceived as a person with a certain degree of maturity and intergrity, and telling your company you will be leaving days before the actual event will most likely be perceived negatively.
Suggestion: speak with your superiors ASAP. Again, I do not know the exact nature and specifics of the business you are in, and it may the case that for some very justifiable reasons the company simply cannot allow you to stay. But in most cases there will be 2 scenarios:
1. Your boss is a person who understands and values what you are going to do since you are essentially aiming higher than where you are right now, which is always good. Moreover, he will understand that your future MBA will mean that at some point in time you may well become a client of his, or, vice-versa, he/his company will be pitching you.
2. Your boss is rather short-sighted and, well, stupid. Then, there is no value to work for such person any longer anyways, and you are doing yourself a favour
Obviously, those are purely practical considerations, all ethical and emotional put aside, since ethics and emotions are very personal areas and no one is to be a judge there.
Hope this experience sharing helps and good luck!