There is something interesting about the retailers that have been targeted and how they have been hit.
There is a tension between, on the one hand, the desire to expropriate the commodities that are sold to you from day to day (for example JD Sport, H&M, KFC and HMV )with the desire to damage the shop more than is strictly necessary in order to loot it.
Obviously there is a danger of reading too much into this, as other business were effected like the old hairdressers up in Tottenham and to some extent these brands represent what is available on the relevant high streets. Intentionally or otherwise, trashing Nando's and KFC has a symbolic quality, especially when another target would presumably have been more profitable.
It also seems interesting how disorder moved outwards from the edge of the inner city to the suburbs more readily than towards the centre of the inner city. Again, there is a danger of reading too much into this. Specifically, Mark Duggan's killing happened to trigger events in Haringey in a particular way that make it unwise to make sweeping generalisations. However, we may be going through a period of transformation in our cities where they gentrification of the centre will be reinforced by the crisis (cf. Tory policy statements on housing benefit in central London). I would guess that in the past recessions have been more associated with a middle class retreat to the suburbs or further afield in London. There is clearly an attempt to make London more like Paris, where the affluent centre is sheltered from rage of the banlieue ('suburb'). I think this could be a seen as a moment of conflict that may determine if this process proceeds unhindered.
It is hard, if not impossible, to explain why trouble didn't spread to Hackney. Factors may include the Hackney One Festival being cancelled. The police have made a recent show of strength with mass arrests on the Penbury estate and were making their presence felt last night. It could just be 'happenstance'. But the successful gentrification of Haggerston, Stoke Newington, Lower Clapton etc. also seems to be a factor.
Edit to add that Imention Hackney specifically as: (a) I know Hackney, (b) it is an example of heading in rather than out of town.