If you are trying to cache the tiles that Google serves, that may be a violation of Google's Terms of Service (unless, under certain circumstances, if you've purchased their enterprise Maps API Premier). That's why gmapcatcher has it crossed off their list. See http://code.google.com/p/gmapcatcher/issues/detail?id=210.
At the gmapcatcher URL above, you will also find a shell script that can download tiles (or so its author says).
There are also other projects that try to make Google Maps available offline:
http://code.google.com/p/ogmaps/
http://code.google.com/p/gmapoffline/
Lastly, if Google Earth can meet your needs, then you can use that. Offline usage of Google Earth requires a Google Earth Enterprise license according to http://www.google.com/permissions/geoguidelines.html.
Note that the preceding page also says: "You may not scrape or otherwise export Content from Google Maps or Earth or save it for offline use." So if you try to cache tiles, that will almost certainly be considered (by Google, anyway) a violation of the Terms of Service.
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