rocknbil - 5:26 pm on Apr 23, 2012 (gmt 0)
Well the first thing to ask is did you change the site URL in the wordpress admin? That may be all you need.
Otherwise the solution is easy, done it many times, and reverted in and out when things when south.
First do a global search in your theme for any hard coded references to .us. Swap them all out. A strong text editor that can search for strings without opening the files is extremely helpful (Homesite here!) Have them ready.
Go into PHPmyAdmin, select export, do a database dump. In this dump, make sure to select the box that says "add /drop table syntax". When you re-import, this is what you want, otherwise it will halt with "table already exists." Also make sure it's set for download (file.)
Download and open this .sql file in a strong text editor that has robust search and replace capabilities (it will be very large and choke many editors.) **Immediately** re-save it as "example-mod.sql" or something.
Do a search and replace for example.us and replace it with example.com. Save the dump.
Now back to phpMyAdmin and select import, import this file . . . done. Upload the revised theme files if anything changed in them.
The only thing I've seen go sideways is some plugins somehow lose settings, and you might have to disable and re-enable them. But if it does . . .just re-import your original unmodified database file (You got the part about save as, right? This is pretty important.) All this takes about 3 minutes.
Once it's working at .com, go back to .us and revise the 301's.