Should be noted that phones aren't like PCs. If you want a fix, you're expected to buy a new phone with the latest software/features.
Though Nokia phones do at least have a degree of software updates available for a short while, but they dry up over time as new models are released (and they discontinue the old ones), and as new versions of S60 are like entirely different operating systems (e.g. S60 2nd ed, 3rd ed, 3rd ed feature pack 1, feature pack 2, 5th edition etc), the lesser versions generally become unsupported and fixes are not universally applicable unlike with a PC operating system where most people run the same version (i.e. XP).
However a darn sight better than some mobile companies that don't offer any form of updates at all (or if they do they charge you for the privilege).
Anyway, is this in the wild? Is it practical for the attackers anyway (complexity and costs involved in firing off such messages etc)? As it's not a virus, trojan or spam, is there any point? It's not like they're earning money out of it so they're not likely to send out millions of texts to kipper S60 phones (well unless the attacker is a Mr. S. Jobs !).
I can only see it being appealing to a few kids who want to annoy their mates, and only if they have the know how to do it.