From OSGeo Wiki
For those who want to organise their own accommodation, transport, etc. Assemble your knowledge and tips here.
There are a number of backpackers in and around town (CBD).
The suburbs closest to the conference centre are Cape Town (CBD, downtown), Green Point, Three Anchor Bay, Foreshore, Schotse Kloof, Zonnebloem, Tamboerskloof, anything in the 'City Bowl', Sea Point, Woodstock.
Orient yourself at the conference map site.