Here in the US, those states that recognize transsexuality, don't require TS's to be sterilized, however some states and the SSA require an affidavit which indicates the surgeries performed before they will change the gender on their records. Some requirements are quite specific about the procedures performed to qualify for a gender change. These are the standard procedures in SRS which will render the person sterile.
So in one respect, no, sterilization is not required. You may present as any gender you choose. However you cannot change the gender on your records without going through SRS (and sterilization) so in that case, sterilization is required.
I didn't see in either of the articles mentioned whether of not sperm/egg banking could be done prior to sterilization. That is the recommendation given to transsexuals who have intentions of later procreation through artificial insemination.
Thomas Beatie, who by the way is only one of many, many, trans men who have been pregnant, probably can not get any of his records changed to male since he has obviously not had a hysterectomy.
-Sandy