I'm not sure anything in your post actually answers his question.

To answer his question: Yes, there are many "SIM-only" (commonly called "prepaid" in the US) options. AT&T has the GoPhone thing, and T-Mobile has a couple of different prepaid options.

You can get smartphone data with both AT&T and T-Mobile's prepaid. A contract-free iPhone (3GS/4/4S) on AT&T GoPhone is a pretty good deal right now. Using an iPhone on GoPhone doesn't require that it be unlocked, as it uses standard AT&T (micro-)SIMS.

The various CDMA carriers and the MVNOs operating off of it has similar deals, though they're not as cost-effective and there's a choice of no or expensive data options.