There is a native tab bar extension in 3.5, and I use it. It works both on Android and iOS.
Bear in mind, though, that it is a bit inflexible. It keeps a separate WebView for each tab. Now, that is nice in some cases. But in others, not. There is no logical reason to tie the concept of a tab bar to that of multiple WebViews.
- one should be able to have a tab bar without multiple webviews
- one should be able to have multiple web views without a tab bar
That said, I don't think the tab bar brings much value unless you need the multiple web views. HTML tab bars work just fine.