My understanding (correct me if I'm wrong) is the credit on the gift card could only be transferred to another gift card using a PIN. If this is true, Sam Odio must have brute forced that PIN which was clearly not part of the experiment. I'd call that wire fraud. Even if there was no PIN Jonathan himself stated that he didn't want this to happen, that the experiment was in sharing change between Starbucks customers.
At the end of the day I find it hard to defend Sam Odio's actions no matter the scope of the experiment. As is often the case, I think he had a potent mix of greed (for money) and ability (to siphon money out of the gift card). Ultimately he ended up with over $500 and gave himself a reality check - anyone in their right mind would feel they have been at least "very surreptitious" if they were in his shoes. Sam wanted an out, and donating the stolen money to charity is the easiest way to spin his actions in a selfless view. From the wording in his blog post you can see he's no better than the so called yuppies he's trying to teach a lesson. The first thing going through his mind was "This is enough money to buy an iPad". Spoken like a true materialist? Not a single mention of the people who contributed that money in the first place.
And finally, just what lesson was he trying to teach here? That sharing spare change is greedy? Let's not forget that Sam treated himself to a coffee with his loot.
I can't help but feel he's getting what he deserves by having his name plastered on CNN and other media. When we dig beneath the surface his actions are truly revealing of his shady character.