It took me a while until I would finally face the issue about iMessages (and their date). The latest released version of the SMS extractor was able to deal with iOS 5 containers and would already also extract iMessages – however with a wrong date.
In order to fix this, I had to treat iMessages as a special case. Thing is, in order to still be able and deal with container files prior to iOS 5 (and the program stay universal), the fact whether iMessages can appear needs to be determined before the actual message retrieval is done. So far I’ve been too lazy to approach this issue, that’s why it took a while. (And yes, I hate legacy support, but I hate it even more when users are left out who don’t or can’t update for some reason!)