How hard would it be? Probably pretty damn hard. I'd have no idea where to begin and I don't know any other programming languages other than html and some php. Also, to have an XS650.com specific app, I'd have to pay Apple $99 per year to be a "developer" and I'd also want to have an apps for Andriod, BlackBerry, Nokia, Palm, etc... Then I would have to update each one with every update to the forum software. So that's probably not going to happen until this site has a huge group of users who want the feature and would be willing to pay for it.
Now there is a third-party app that works with vBulletin sites, but I would have to sign up for it and install a plug-in to make it work. Then you'd have to pay $2.99 to download the app and get to XS650.com through the app. As with many apps, you are limited on the site features that you can use though the app. As of right now with the third party app, you can't search and you can't register through the app. It also doesn't support the way threads are categorized into topics using the tag system. Then there is also the concern that I'll do something on my end with the site that the third-party app won't support, and the site won't work anymore on the app you bought just to use for this site, and you'll be pissed. Even with all that, it still looks pretty promising so I'll look into more. It'll probably be something that happens when we go to vBulletin 4.0. (The site is on 3.8 right now and will be upgraded soon).
Another option that might make the site even easier to use with your phone would be a mobile skin. You can select the style you want to view the site in now using the drop-down menu in the lower left corner of most pages. I could add a style that is for mobile phones. I'll work on that right now.
It sounds like one of the main reasons you want an app is for your signature. I read something once were a guy changed his desktop email signature to say "sent from my iphone" so that it was socially acceptable for him to send one line emails with shorthand and misspelled words. You could always do that here
Or when you post using your phone, at the end of each post you could just type "via iphone".
via Android