The week after an exploit that takes advantage of the way that iOS devices handle PDF files was announced, Apple has released a patch designed to fix the problem. The patch is included in iOS 4.3.4 for iPads and later-generation GSM iPhones and iPod touch devices; CDMA iPhone 4 users can install iOS 4.2.9. In either instance, the software update must be downloaded through iTunes; the download is a complete system image.
Apple required as much time to release this patch as it did last year, when addressing a related JailbreakMe.com exploit. It's unclear if that window between Day 0 of the exploit and its resolution is simply as small as one can expect, or if Apple's development resources are so committed to the forthcoming iOS 5 that security issues are taking a back seat for now.
In any event, I'm looking forward to iOS 5, if only for the promise of incremental updates to the mobile OS, rather than the current practice of requiring users to download the complete system image every time a new vulnerability is found.