I started some mining at home on my sig rig earlier in the week but I don't really think it's worth it... might do a bit more though just as a hedge to get something out of it (Slush's pool). When I say a hedge, I mean in the unlikely even that this one day has like 5% of the global economy using it for example, even at a couple decimals off of one Bitcoin in that instance (possible if unlikely future) it would still be worth a tonne of fiat currency.
Once the ASIC's come widely onstream it will be a rich mans mining game as only those with big budgets will be able to secure enough relative hashing power in the overall hashspace (with it's spiking difficulty) to turn a decent profit. It's relative hashrate that will count, not your individual GHps.
Returning to the OP's point, I think he was actually asking if mining does anything of 'value' beyond the actual act of mining the coins as their own reward. Like say folding for the gain of medical research has ethical value you could say.
And, no, no it does not. But, the more miners there are, the quicker, better and in theory more secure Bitcoin is as a network/currency/whole.
