Yes, Well - Been there, wished that ... I think I expressed the same wish in this forum some two years ago. But I don't think it's about to happen because my understanding is that Avantgo requires the news site provider to re-package its content before submitting it to the Avantgo site - and I suspect that Captain Danny et al have better things to do with their lives ... Also, most (all?) of the sites accessible from Avantgo are news sites - not bulletin boards like PPRuNe - and it wouldn't be easy to condense PPRuNe down to a size compatible with the memory limitations of handheld devices ie. what interests me on PPRuNe wouldn't necessarily interest you - and who gets to make the decision as to what gets left out and what gets included on the Avantgo edition? Plenty of opportunity for major whinging!
That all having been said, you can browse PPRuNe on a handheld device - using the version of IE included with WinCE, or (in my case) using EudoraWeb on a Palm. I have done it, and it is readable, but it demands rather more patience than I generally have available these days - 9600 bps over an IR link to a cellphone is s-l-o-w (and expensive!)! If you do want to test your patience and try it, I suggest that you use the URL's that take you directly to the forum you want to browse (can't remember what they are now, and they don't seem to show in the address of my browser like they used to).
Have fun with your handheld (and be warned that they very quickly become totally indispensable!)