After Thursday's iPhone OS 4.0 event, when asked why multitasking was being excluded on devices older than the iPhone 3GS, Apple said that the older devices just couldn't do it. However, that wasn't quite true. A developer, who's been messing around with the iPhone OS 4.0 preview, has found that by simply switching just one variable in preferences, multitasking can indeed be enabled on the iPhone 3G.
As far as we know, there won't be a flag in the final release version of the OS, but it looks like you can switch it on by tweaking one file on your own phone (which will require jailbreak). Of course, jailbreakers already have access to multitasking, and they'll be able to use Apple's official method as well, it seems.
Steve and Scott Forstall have a little explaining to do -- why were we told yesterday that all of the devices before the 3GS couldn't multitask? It's certainly possible that they don't do it well, or that they can't handle as many processes as the 3GS might be able to handle. Unfortunately, this looks like Apple is trying to force an upgrade rather than get the software right (as this NSFW blog post complains). It was even mentioned yesterday (from the Engadget liveblog): "If that's an incentive for them to upgrade to a new device... terrific."
We'd hope that Jobs and co. wouldn't purposely force a hardware upgrade, but it would be nice to to have some clarity about exactly what the problem with is multitasking on an older iPhone.