Assuming a mobile service needs to be launched in 6 months time, does it make sense to go straight to HTML5? Will the market be ready?
The recent release of the first version of JQuery mobile looks promising, for example.
There is a huge temptation to bypass native apps altogether (even with tools like PhoneGap). Not only does one avoid the app approval process, but, just like having to download plugins causes friction for desktop websites, giving users the opportunity to directly interact with a mobile-specific site as if it were a native app sounds like a big win all round.
Downloading an app in today's modern phone is almost as frictionless as entering a website.