Last night on SNL, Jake Gyllenhaal briefly made two legends soar in the same instant — the gay Dreamgirls thing (can’t decide if this was an Oscar-campaign assist or a futher tear-down) plus the old Brokeback Mountain gay-cowboy mystique. Hilarious-perfect. In one fell swoop he won instant forgiveness for Jarhead and upped the anticipation levels for Zodiac (Paramount, 3.7)