iPhone 4 Retina "apple-touch-startup-image" for Web-apps

Question

This has been asked multiple times here, but without a solid and understandable answer. This is a web-app, not a native-app.

I'm using:

<link rel="apple-touch-startup-image" href="images/startup.png" />

to display the startup image. It loads fine if the image's resolution is 320x460. I tried using the retina's resolution which is 640x920 (40px are taken out by the status bar), that didn't work. I've tried the @2x thing, that failed too.

Is it even possible [yet]?

Answer 1

The documentation (found here) says:

On iPhone and iPod touch, the image must be 320 x 460 pixels and in portrait orientation.

I have tested providing different sizes, but the if the size is not exactly 320x460, the image is simply ignored. There is no clear statement from apple whether it is possible to include high res startup images, but forum posts (eg here: Apple Dev Forum) suggest that it is currently not possible.