Seal of Command should now be used in favour of Seal of Righteousness in virtually every (PvE) circumstance. You should only be using SoR in AoE situations anyway, but in these circumstances SoC should now be able to pull out a meaningful DPS lead, Seal of Command's cleave effect range seems to be roughly melee range, i.e. ~5 yards, One target cannot be hit with multiple SoC cleave effects from the same source, As indicated, Seal of Command's cleave won't work with Divine Storm or Hammer of the Righteous, but the basic SoC proc continues to work with these skills Seal of Commands' Cleave will break Crowd Control, The Cleave effect counts as an AoE attack, and AoE-damage reducing effects will affect this proc (e.g Factions Champions in TotC), Seal of Command should henceforth be known as "Seal of Cleave"
SoC Cleave procs will chain to nearby attackable neutral NPC's, so be cautious
Taking the talent is a tough call, the trade-off largely depends on your raid make-up. If present in Moonkin heavy raids should drop points from Swift Retribution, Warrior/druid heavy ones will look to Vindication, Paladin heavy ones probably won't be picking up Imp Blessing of Wisdom. SoC's probably worth it, but will stimulate many a lively discussion.
Have fun with it :).
ADDED: It strikes me that I haven't really distinguished between PvP abnd PvE. Personally, I think that the relatively weak Judgement damage of SoC continues to push SoR as the superior skill. Breaking CC certainly doesn't help either.