I am a male and have practiced nursing for about thirteen years after a decade working in the business community as a CPA. From that perspective I have a few comments:
There are places where you will find discrimination by co-workers who feel that as a male you are invading their (female) turf. Fortunately, in my experience such cases are the exception, but they do exist. When they do, they are rather blatant in their behavior as they have no doubt gotten away with it for years and have a manager who is unwilling to confront their core group of nurses.
Similarly, I have witnessed some rather blatant discrimination by some individual instructors against males as nursing students. But again, this is the exception in my experience and I must say I have seen the opposite: males being treated more favorably than their abilities warranted. Nursing school evaluation, clinicals in particular, can be extremely subjective. If a nursing instructor wants to paint someone as "unsafe" or disorganized they can certainly do so with most any student. For whatever reason, it seems that men do drop out of nursing school disproportionately to their numbers. Some of this is likely due to financial considerations; but, I have to say a substantial number of men I have talked to just tired of the nursing school BS.
This also seems to carry through after graduation: Recent research shows that men are far more likely to leave nursing within a few years than are women. But rather than discrimination, I suspect that they leave the profession for the same reasons that the women do.
You will also hear stories about how males are either paid more or advance more quickly than women in nursing. I do see a disproportionate number of males in leadership positions at some institutions but the reasons for that may have nothing to do with gender bias. Males seem to become certified, further their education, maintain full time uninterrupted service etc. disproportionately as well. On the other hand, when I assumed a management position at my 700+ licensed bed hospital a couple years back, there were no male educators, case managers, clinical coordinators, house supervisors, QI nurses etc at all, let alone nurse executives. I would attend meeting after meeting some days and never see another guy at the table.
To summarize, there are some serious problems within the nursing profession which must be addressed. But for the most part, gender issues should not be a major concern for you.