Right now, Hubski is still just about small enough that hubwheels are accurate representations of the success of a post. However, as the site grows, it seems to me that they will get increasingly less representative and more useless. It seems inevitable that at a certain point every post that achieves any success will have a full hubwheel and therefore there will be no visual differentiation between a reasonably successful post and the best post of the year.
I'm sure this argument has been made before, and better than I have been able to, but I think it's worth stating to ensure that as the site grows it's design metaphors evolve with it.
The best system I could imagine would be a logarithmic system which could easily be adjusted as the site grew further. Each successive dot requires more shares to be filled than the last, resulting in a hopefully quite even distribution of posts across each amount of dots. I believe the other site uses a similar system.
Just throwing it out there. Thanks for reading.
We'll see if it is necessary when the time comes. Since there is a 'shared by n' link in the header, it might not be necessary. Also, as circle-dotting shares the post or comment, people are a bit more reticent to circledot than they are to simply upvote.
As an aside the 'shared by n' link is as much as a tracking of number of shares as it is a way to see which users appreciate the content.