Let's kick off a directed discussion about this. Please check out the general conversions thread if you need to see some example monsters and discussion on how to convert.
First Encounter: Goblins in the Streets!
In 3rd ed terms, this is spread over three encounters. One with a few generic goblins, another with a bigger force of goblins with a warchanter a few rounds later, then another few rounds until a fighter against a goblin commando on goblin dog and some more goblins.
In 4E terms, there's no time for a 5 minute rest so it may be reasonable to think of this in terms of one big encounter.
The normal goblins can probably be minions, though I'd suggest more obviously mixing them up. Some kind of 'sticky fire' attack can probably be added to some for hurling burning objects. Having some kind of 'on a attack roll of 1, a single minion is taken out by self or friendly fire' rule is probably reasonable and fun.
For the rest, possibly just having them trigger at certain round counts within a reasonable range (putting the whole battle within the equivalent of a 20x30 area, for instance) - keeps things frantic and fun as people break off to save people.
So, monster types:
Goblin Minions (Level 1 Minion)
Goblin Arsons (Level 1 Skirmisher or Artillery)
Goblin Warchanter (Level 1-2 Controller Leader)
Goblin Commandos (Level 1-2 Skirmisher)
Goblin Dog (Level 1-2 Brute)
Possibly the goblin commando on goblin dog actually works out as one creature instead of two.
For reference, the D&D 'goblin racial' appears to be:
Goblin Tactics (immediate reaction; at-will)
Whenever a melee attack against a goblin misses, the goblin may shift 1 square.
Which seems decently in flavor (dancing away cowardly, etc)
Doing something like:
Round 1: 5 Goblin Minions (125 xp)
Round 2: 4 Goblin Minions (100 xp), 2 Goblin Arsons (200 xp), 1 Goblin Warchanter (100-125 xp)
Round 6-8: 8 Goblin Minions (200 xp), 1 Goblin Commando (100-125 xp), 1 Goblin Dog (100-125 xp)
Alternatively, make the commando fight (Die Dog Die) a completely separate fight. One option is to not use the minion mechanic at all, and use a lot more level 1 actual mobs... but I think it fits to be bowling over a lot of the initial goblins.