Depending on what market you are trying to target iPhone users or Android users? Frameworks like the above are nice because in order to submit an app to the Apple Store, it needs to be written in Objective C and on a registered Mac computer (virtual machines do not work). Hence, if you use a framework like phonegap, you just need to make your app and you can pay a small fee for them to convert it into all languages.
I currently develop android apps with phonegap (but i prefer using Java because i have way more control and i can extend & inherit whatever i want without worrying about cross API madness.
When developing apps, it is alright to develop for one certain kind of device (iPhone vs Android) but you have to think, a lot of successful companies develop on BOTH, not just android or iPhone. I personally have never owned an iPhone and almost guarantee that i never will, HOWEVER iPhone users are very important because they hold a HUGE side of the mobile app market.
FYI, i would suggest posting this in the “Other Discussions” part of the forum :) Hope that helped, Goodluck!