On the Dashboard page in the admin, you can view your financial graph or the financial stats report based on either an accrual or cash accounting basis.
Accrual Basis accounting includes all payments, both expected and received. Cash Basis accounting only includes payment received. Basically, this means that viewing the financial stats using the accrual basis will include orders that are in 'Awaiting Payment' status, while a Cash Basis will not reflect payments from these orders that hasn't been received.
For more information on Accrual vs cash accounting, check out http://en.wikipedia.org/wiki/Basis_of_accounting. To determine which accounting basis is best suited for your store, we recommend consulting with your accountant.