OK, I'm biased. I detest SMS spam - which I define as ANY unsolicited SMS, even from my operator telling me about new services. I go out of my way to ensure I never receive any - putting my fixed-line number on web forms unless they have a clear & unambiguous marketing opt-out. British Airways for example is very clear that it will only send SMS about things like flight time changes, never for marketing, and that's OK.
Personally I'd never opt in for SMS advertising, and I'd certainly never buy an product or service marketed in that way. I've even chased down culprits and informed them of my punitive fees for deleting future unwanted messages. I prefer any marketing, news updates etc to come through via email, where it's much easier to scan, filter & prioritise messages - and read them as & when I have time.
Posting to ForumOxford recently, I thought about what it would take to persuade me to change my mind on this. The answer was an upfront payment (in cash or credit to my mobile account) of £3-£5 per received message.
The other option would be to develop SMS clients that are similar to today's email clients, so that rather than getting a "You have mail!" alert each time a message come in, you can just look at your inbox. However the problem with this is that it would mix up texts I want to receive immediately and would allow to interrupt me (friends, work contacts), and ones which have no realtime importance (advertising). And I don't think I can be bothered to set up a filter for who I'm happy to be interrupted by, plus occasionally I get urgent texts from unknown numbers ("Running late, in a taxi, there in 15 mins").
The other thing is that SMS marketing is roughly now where email marketing was in 1996 - "you have mail!"... cool!! But once you get to 'You have 94 unread SMS' you need to be a bit harsher in your attitudes.
Hopefully handsets will soon ship with preloaded SMS antispam software, and your SMS client will have Inbox / Sent / Spam folders in the same fashion as today's webmail & desktop clients. Then you could just sift through the rubbish once a week to look for anything that's fallen through the gaps - and you could mark the updates from your bank / hairdresser / favourite bar as 'not spam' to whitelist them if you really wanted.