WASHINGTON, June 27 — In one of the first consequences of its landmark ruling on gay rights on Thursday, the Supreme Court today set aside the lengthy prison sentence imposed on a gay Kansas teenager for having had sex with a younger boy. In a brief order with little elaboration, the court vacated the 17-year sentence imposed in 2000 on the defendant, Matthew Limon, and returned the case to the Kansas courts "for further consideration in light of Lawrence v. Texas." The case of Lawrence v. Texas, which was decided on Thursday and overturned an Texas antisodomy law, upheld the...