The author forgets that GCC / the GNU toolchain alone is not sufficient to package, sign, and distribute a .ipa - instead, the developer is bound to Xcode, signing certificates, and the whims of the App Store approval process.
By declaring ActionScript, C#, and Java (all of which have open compilers and virtual machines) "vendor lock-in", the author glosses over the fact that the iPhone OS toolchain is not an open one, in fact, arguably more restricted than all of the above. Make no mistake - I'm not arguing that any of the above are "open" platforms, or that open platforms necessarily make for a better product ecosystem. But I would like to offer a correction to the article's imbalance.
Anyway, I wasn't getting my hopes up. The dream of "write once, deploy anywhere" software is generally one that disappoints.