Actually, for a long time I did offer a plug-in for mobile uploads; the issue was around keeping it updated and Sprint was always changing their emails to try and prevent people from being able to directly access their own images.
If PhotoPost was a single service, it would be easy to put something together - an iPhone app even. But the only method we can use for our customers is email and many people had trouble getting even email access setup properly or scheduling the cron job. Couple that with the requirement that all mobile uploads get processed into a single category (considered just putting them into a person's upload queue).
I'm open to the idea of bringing the mod back (I still use it and the code to support the category is still there), but supporting it can be difficult.
Please do not PM me for support or sales questions. Thank you for your understanding.