I've seen some funny behavior on a computer I use PortableApps on. Trend Micro OfficeScan, following (presumably) an update, now goes bat **** crazy on Autorun.inf (Windows XP machine, but it got the KB update that disabled autorun on rewritable removable devices, so it normally doesn't use autorun.inf anyway, except to show the device name/icon in My Computer (which, ironically, still do show up). It does this every time the drive is connected. Can't even delete autorun.inf to make it not do that, at least until I can get it home.
Maybe the PortableApps.com Platform shouldn't be putting an autorun.inf drive in the device's root? Windows 7 is gaining ground, and even though the majority of the Internet still uses Windows XP, most XP users use Windows Update and would have that update. I'd bet there are fewer people using an OS that can autoplay rewritable removable devices than people using an OS that can't, by a pretty wide margin. And I do remember when XP got that update, a lot of regulars here agreed it was the right decision.
A better way, going forward, in my opinion, would be for the platform to be able to "drop" a "listener" on the host PC, carrying with it a warning to only do so on a computer you own or have permission to install software to (e.g. not work or school) if anything.