For those who would like to get GP and CRM integrated, I am highly recommend using Scribe. Scribe provides a template for the integration. All of the standard fields are pre-mapped, what you needed to do is to modify the template for any custom fields that you created in CRM or GP that you would like them to integrated.
In order to do the integration, you need eConnect for getting data out of GP which eConnect is provided to you for free. You also need Scribe Workbench (Tool to define the mappings), Scribe Insight (Like a job scheduler), CRM Adapter and GP Adapter. The cost of the Scribe pakage is around $4,000, which can save you a lot of time and effort comparing to other integration methods. The other benefit of using Scribe is that you can use Scribe for other data integration and migration.