Well, I was able to do this by modifying the GoogleMpas web part. I cloned it, and made the following changes that I thought I would share with everyone.

in the "Document properties" region:

protected CMSDocumentsDataSource mDataSourceControl = null;

    /// <summary>
    /// Filter name.
    /// </summary>
    public string FilterName
    {
        get
        {
            return ValidationHelper.GetString(GetValue("FilterName"), repItems.FilterName);
        }
        set
        {
            SetValue("FilterName", value);
            repItems.FilterName = value;
        }
    }


    /// <summary>
    /// Data source name.
    /// </summary>
    public string DataSourceName
    {
        get
        {
            return ValidationHelper.GetString(GetValue("DataSourceName"), repItems.DataSourceName);
        }
        set
        {
            SetValue("DataSourceName", value);
            repItems.DataSourceName = value;
        }
    }


    /// <summary>
    /// Control with data source.
    /// </summary>
    public CMSDocumentsDataSource DataSourceControl
    {
        get
        {
            return mDataSourceControl;
        }
        set
        {
            mDataSourceControl = value;
            repItems.DataSourceControl = value;
        }
    }

In the SetupControl method, in the else block add the following:

	//Additions to Allow GoogleMaps to work with Filter Control
            this.repItems.FilterName = FilterName;
            this.repItems.DataSourceName = DataSourceName;
            this.repItems.DataSourceControl = DataSourceControl;

On the WebPart, connect these new properties by creating the following new fields:

FilterName Text size 200, allow empty values
DataSourceName Text size 200, allow empty values


Then you should be able to use a datasource tied to a filter on the GoogleMaps webaprt. Hopefully, leaving this out of the webpart was just an oversight by Kentico.