https://sites.google.com/site/physicalbitcoin/howhttp://blockexplorer.com/ should be blockchain.info because the latter has better uptime.
There are several iPhone App’s - drop apostrophe and cap, 'apps' is not possessive or proper/trademark, also don't leave out Android apps.
QR-code - no hyphen, find-replace all
Mt. Gox - no space after the dot, find-replace all
Just Google, “bitcoin iPhone,” to learn more. - remove commas
http://manpages.ubuntu.com/manpages/natty/man1/zbarimg.1.html - may be a little too advanced; Linux, plus you have the step of transferring a pic to a computer, and some people might not have any camera, phone, digital, or webcam. Are you sure it's a readable QR code under the seal? Super tiny ones often won't scan. More thought needed on this.
to reap the bitcoins - to sweep the bitcoins
which makes the bitcoins remaining in circulation more valuable - needs period at the end.
"beta-software" - beta? might be debatable, but it could either lose the hyphen, or be replaced with "in beta"
the exchange rate of bitcoins has been rising - better to put that in absolute terms, such as "the Mt.Gox USD exchange rate of bitcoins recently reached an all-time high of $34.51, exceeding the previous all-time high set in 2011, of $31.91." or something to that effect, since there might be a sudden drop at any time.
Gotta sleep soon, so I'll see if I can work on the other pages "tomorrow".