Excel 2007 Add-in: Synchronizing Tables with SharePoint Lists:
This add-in accompanies the MSDN article "Publishing and Synchronizing Excel 2007 Tables to SharePoint Lists", available in the Related Links section. The add-in allows you to publish a read-write list to Windows SharePoint Services.
While this is nice, it seems to be incomplete, compared with the previous capabilities in Excel 2003. It will allow you to create a list in Excel 2007 and publish it to SharePoint, but there doesn't appear to be a way to link to an existing list, edit it offline, and synchronize it back.
This is a significant lacking feature, as information workers typically use Excel...not Access. Since SharePoint is really an information worker enabler, the removal of this feature set from Excel is short-sighted (unless the real reason was to sell more copies of Access).