Steve Chapman of Rose Business solutions has a nice write up on the new AP and AR reconcile to GL functionality. Keep in mind that there appears to be a bug in the AP functionality if you pay items with a credit card in GP but I think that ultimately, this will prove to be a very useful utility.
AP/AR to GL Reconcile
Payables & ReceivablesGeneral Ledger & Financials
Archived post from 2008. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.