Android G2 phone from Ebay = $140 unlocked.  Works on TMobile.  Touchscreen is nice - Google apps.  But it's not really as well designed outside (and the graphics are hoaky) as an iPhone.  It does have a cheap camera (again not an iPhone) and no speakerphone (perhaps a benefit, rather than limitation).  There is really no "free" wifi, since you have to have the data package from the carrier (TMobile) it costs data throughput (however it's cheaper).  Unlocked from China, it's not going to have any of the TMobile apps (hotspot, Fave5, etc.).   But the G1 directly from TMobile is pretty sweet too; it contains a full QWERTY keyboard.  Consider a data pack and your phone is going to charge at least $60.00 a month (with very few minutes to talk).  Since these are Android phones, all the Android apps work on them.  Trust me though the SSH is not what it's cracked up to be.

iPhone doesn't run alot of stuff until you unlock it, but it's a better device, however, it's comparable to a NetBook in cost?  Why not just carry a danged computer with a softphone application, like Skype?    Unlimited Skype trunking to PSTN is about $30.00 a year.

You can use Skype on the iPhone with a new AJAX interface that refreshes the Opera browser, but it requires:

1) Data throughput charges
2) Skype minutes, since it's going to be a PSTN trunked call.
3) Unlocked G3

http://blog.tmcnet.com/blog/tom-keating/skype/skype-on-iphone.asp