Sharepoint - Moving a WebPart to a different zone on a page

Use the SPLimitedWebPartManager.MoveWebPart method:

string zoneId = "TopZone";           // ID of the WebPartZone control
string zoneIndex = 0;                // Location of web part within zone
string webPartTitle = "Sales Tips";  // Title of web part
string filename = "default.aspx";    // Filename relative to SPWeb object

using (SPLimitedWebPartManager webPartManager = 
    site.GetLimitedWebPartManager(filename, PersonalizationScope.Shared))
{
    try
    {
    	foreach (WebPart webPart in webPartManager.WebParts)
    	{
    		if (webPart.Title == webPartTitle)
    		{
    			webPartManager.MoveWebPart(webPart, zoneId, zoneIndex);
    			webPartManager.SaveChanges(webPart);
    			break;
    		}
    	}
    }
    finally
    {
    	webPartManager.Web.Dispose();
    }
}

In addition to the answer from Alex, be careful when you iterate your site collections and sites. If you do this from for example a console application where you have to establish your own context, you will run out of memory very fast if you forget to dispose your SPSite and SPWeb objects while iterating (eg. sites.AllWebs).

read and understand the disposing guidelines on MSDN:Best Practices: Using Disposable Windows SharePoint Services Objects