Today I read (here) that the University of Georgia has joined the growing list of colleges and universities and other public places to designate one or more "gender-neutral" restrooms. The impetus for UGA's decision was a desire to accommodate transgender and transexual students, for whom gender-specific bathrooms can be uncomfortable, hostile spaces. Gender-specific bathrooms also present an unsatisfactory, limited set of options for those who don't identify with either label on the door.
Does Title IX have anything to do with the increasing accommodation of these students? I think the answer is yes, though not directly.
First, while Title IX has been the impetus for "potty parity" in education buildings (for example, ensuring that there are sufficient women's restrooms in college buildings) I could find no evidence that plaintiffs have argued that a lack of access to gender-neutral bathrooms in federally-funded schools violates Title IX. This is probably because the courts are unsure when and whether to treat discrimination against transgender plaintiffs as sex discriminaton under federal civil rights laws. For example, several courts have rejected transgender employees' sex discrimination claims under Title VII, with the notable exception of the 6th Circuit's decision in Smith v. City of Salem. (See generally this helpful summary published by the American Constitution Society). A transgender plaintiff seeking to challenge the lack of effective access to restrooms as a violation of antidiscrimination law would have better luck under state and local laws, which in some jurisdictions prohibit discrimination on the basis of gender identity as well as sex.
Title IX does, however, require colleges and universities to take reasonable steps to protect students from sexual harassment at the hands of teachers and peers. Administrators might reasonably anticipate that a biological female student identifying or presenting as male, or biological male student identifying or presenting as female, is at a high risk of harassment in either gender-specific bathroom, depending on the circumstances. At least one court has held that Title IX protected a transgender (MTF) plaintiff against direct sexual harassment by a professor, see Miles v. NYU, 979 F. Supp. 248 (SDNY 1997). Thus, risk averse colleges and universities might decide to designate a gender-neutral bathroom as a way to preempt or curb existing harassment in order to avoid liability. (For more on Title IX and transgender plaintiffs, see Leena D. Phadke's comment in the Kansas Law Review.)
Another possible connection between Title IX and gender-neutral bathrooms takes into acount the advantage of gender-neutral bathrooms to a different potential constituency. Parents, especially fathers, might wish to avoid gender-specific bathrooms when taking care of their opposite-sex children. Title IX and other antidiscrimination laws have helped generate awareness about the harm to women done by institutional presumptions that only women are responsible for child care.
In sum, I note that neither the state of Georgia, the city of Athens, nor the University appear to prohibit discrimination on the basis of gender identity. This seems to suggest that to the exent UGA's bathroom decision was influenced by any applicable antidiscrimination law, Title IX indirect relationship to gender-neutral bathrooms is the only possibility.