I have been at Georgetown for 3 1/2 years, both as a grad student and an employed research assistant.
Religion is a part of the school in so far as there are public announcements about Jesuit services, prayer services, and other religious meetings. Nothing is required. If you are a girl, don't expect to get birth control from the health center for "birth control" reasons, they provide it for other needs. Also, no condoms, but there is an undergraduate student organization that hands them out daily in the student courtyard. As someone else said, the science is pure science, no religion involved. I was required to take an ethics class, which I actually think in theory was required because of Geortetown's faith, but religion played no role in the class at all. It was more about presenting truthful vs. false data in a scientific publication and who's name gets put on the paper, etc.
My two bosses are Muslim and Jewish and the school just built a center for building communication and understanding between Muslim and Christian religions. While the Jesuit faith is an important part of the school, it is also the most religiously tolerant school you can imagine - more so than many schools who claim no religious affiliation.
There are crosses hanging in the hallways of the hospital and also morning prayer for patients and visitors who wish to participate. You frequentlly see the Chaplain as well, but again, this is for those who wish to use the services, nothing is forced on you and if you chose not to particpate there is no guilt or anything of that nature involved.