In the Rulebook, under Rules, Combat, Active Abiliites:
So as the rules stand in this outgoing edition: Yeah, you can block active blaster and (non-sunder) melee abilities with a shield.
Quote:Active ability attacks that use weapons must hit the opponent on a legal body target, in order to count. The exception to this rule is the “sunder” effect. A sunder effect counts if it strikes any legal body target or the item that is being targeted so long as that item is a melee weapon or shield. Do not strike props or blasters.
Active ability attacks that use packets count if they hit a legal body target or any object that is currently held, worn, or attached; this includes shields and melee weapons.
So as the rules stand in this outgoing edition: Yeah, you can block active blaster and (non-sunder) melee abilities with a shield.