Since we have no logo restrictions of our own, we fall back on current USA Swimming regulations regarding advertising.  Currently, they are as follows (2006 USA Swimming Rules and Regulations, Section 102.9):

Insignia:  May not wear the insignia and/or name of any club or organization which they are not entitled to represent in open competition, if such action is objectionable to such club or organization.

Advertising:  Limited to a single logo no more than 1.6 X 1.6 inches, unless it is the manufacturer’s logo.