As the reader I addressed BOTH uses due to it's ambiguity due to the frequently lazy nature of message boards. As the writer you need to be proactive. Regardless if you are technically accurate, your goal is to communicate your idea, which requires understanding your audience. In this case, the audience, also writers on this forum, often use it incorrectly, as Melgross stated.
You can see from the number of posts that both Melgross and I have been on this forum for some time. You can look at our specific posting history to know that we often try to be clear in our writing. If Melgross had wrote what you wrote, iPhone 3Gs, it wouldn't have been ambiguous to me because of my familiarities with his posting style. I'll take note of yours but there isn't years of history for me to understand the person behind the comment at this time, hence the ambiguity.
It's not a big deal, and you obviously can write well and form good arguments, but I think it's one you should consider when posting on any forum. Unfortunately, this is not the "real world" and you will have all ages, cultures, and education levels reading and replying. When in doubt... clarify.