For anyone interested in a similar, slightly higher specced, hackable ex-consumer device for next to nothing: ZipIt Wireless have been clearing their old "ZipIt Z2" messenger range for some time now.
<a href="http://linux.zipitwireless.com/" rel="nofollow">http://linux.zipitwireless.com/</a><p>ARM9 ~300Mhz, 32MB RAM, wifi, QVGA display, keypad, mainline linux kernel support, etc.<p>Decent sized hacking community: #zipit on freenode & sites like <a href="http://mozzwald.com/" rel="nofollow">http://mozzwald.com/</a><p>Believe prices are as low as $18 for a single one, or $10/unit if you buy 16. We bought around 20 in a group buy at our local Hackerspace. Not quite cost of postage, but still pretty cheap.