May 19th. Still time for an event to be announced.
They might have time but again, why would they steal WWDC's thunder? And since most of the highly anticipated updates to the iPhone are software-related and won't be out until WWDC (presumably) why would they go out of their way to hype new iPhone hardware prior to WWDC? Apple seriously runs the chance of crying wolf if they overdo it with the hardware when the software stuff isn't out yet.
I stand by my prediction. I think they're release new hardware first without a lot of hoopla, let the Mac forums and blogs and news media go crazy with it and then they'll extend the hype even further with all the software at WWDC (enterprise features, third-party apps, new version of the SDK perhaps, iPhone OS 2.0, etc.)