I see both sides, really ....
On one hand, sure - companies need to be as proactive as possible about addressing security holes.
On the other hand, security issues are popping up more and more often as all the software (and the operating systems) out there increase in complexity and features. Like one of my software developer buddies used to always say, "If I'm 99% accurate in all my coding work, that still means I'm creating an error in every 100 lines of code I write."
Companies like Apple are actively doing relatively large code updates to things like the iPhone's firmware, and trying to get them done on some kind of schedule. The optimal way to handle bug-fixes is normally to submit them on the "to do" list of items to correct by the next official release of the code.
Demanding an immediate security patch for the iPhone essentially means you want them to stop what they're doing, give that bug top priority, AND ensure the change doesn't break anything else either in the *current* code, OR in the rest of the updates they're in the middle of adding. Then you're going to push that big update out to everyone's iTunes, costing Apple a load of server bandwidth and users a big inconvenience (plus the inevitable flash updates that go wrong, causing bricked phones and support calls).
If they know OS 3.1 is due out soon, they're probably taking their chances on putting the security patch in with it, instead -- and I don't necessarily blame them. How many people are likely to really want to blast malicious SMS's out and attempt to illegally take over people's iPhones, all within the time-frame version OS 3.1 is done? Probably less than the number who will have problems doing the upgrade....
Good! Finally someone will light a fire under Apple's lazy butt. It's time Apple was held accountable for things like this. They need to realize that security issues that put their users at risk need to be taken care of ASAP -- that means not taking their sweet time to issue a fix. A month after they've become aware of it is RIDICULOUS.