http://www.techcrunch.com/2009/10/13/google-waves-little-secret-it-already-works-on-the-iphone/

<<Google Wave, the search giant’s latest experiment in post-email communications, is hardly out the gate, with some of the first 100,000 private beta testers still waiting for their invites. (I just finally got mine today, two weeks after launch). But Google Wave already has a few secrets. The one that surprised me is that even though not that many people can use it yet, Google Wave already works on the iPhone.>>

Is this really a secret? Didn't everyone with a Google Wave account and an iPhone try this already? IIRC, it always worked with the Sandbox accounts too...

Yep, I tried it right when I got my Wave account.

This is done using well-documented Apple specific meta tags and JS.

<meta name="apple-mobile-web-app-capable" content="yes" />
<meta name="apple-mobile-web-app-status-bar-style" content="black" />

See here:
http://developer.apple.com/safari/library/documentation/AppleApplications/Reference/SafariHTMLRef/Articles/MetaTags.html

The real issue is that once you launch as a Web App you cannot change the URL. Any link will launch Safari. Thus, all links in your Web App should AJAX load into elements within a static container.

For modern well-engineered applications such as Wave this is easier than for "normal" folks who have some sort of legacy paging or a more "hacked" structure. If you don't have a really good reason to go this route with your Web App it would usually not be worth it.

And for some shameless self-promotion: http://www.apple.com/webapps/entertainment/totlolvideoforkids.html
Same setup, "hacked over" a paged site. First released in April, 2009.

i was sad when i tried it on my android phone and it wouldn't work =[

I don't have an iPhone and I don't have an Android Phone so I wouldn't know :-).

It was demo'd at I/O on an iPhone...

At I/O they not only demo'd it, but also explained that they can do this thanks to Google Web Toolkit..
http://code.google.com/webtoolkit/