hello,
The idea of a link wheel is to have several social sites with articles or profile links all pointing to your target page (or hub) and also all pointing to one of the other social sites so they form a chain eventually circling back to the first social site.
The inward links are like the spokes of a wheel to the hub from the outer ring of social sites.
There are several guys using this and it seems to work for long tail keywords at least but there is also a lot of bull about using 'High PR' social sites to propel yourself to the top for any keyword.
