The lead engineer behind Facebook’s yet-to-be-launched native iPad application left the company out of frustration with continual delays around the release of his work, according to a blog post he published today.

His move underscores the fact that Facebook has not had a major mobile-related launch since November of last year at a critical time when Apple and Google are moving full-steam ahead with the Android platform and the iPad. We’re expecting to see a big announcement out of Facebook on its mobile strategy in the next two to three weeks, however.

The developer Jeff Verkoeyen said that even though Facebook’s iPad app was largely ready to go in May, the company held off on launching it for several months because of undisclosed reasons (presumably Facebook’s complex relationship with Apple or indecision over how much to invest in native versus HTML5 in the short-term).

Verkoeyen is moving to Google where he’ll work on the mobile team, after being employed at Facebook for less than two years.

Verkoeyen wrote:

“You probably saw the app when it was infamously leaked via Techcrunch. It was feature-complete by then and for reasons I won’t go into details on the app was repeatedly delayed throughout the summer. Over the past 8 months I dedicated a significant amount of time toward building this app, sometimes putting in over 80 hours of work in a given week in the hopes of meeting the “perpetually moving two-weeks-away launch date” every software developer fears.

After the app reached feature completion in May and I was told that it was going to be delayed yet again, I stopped working on the project entirely. A few weeks later I decided to focus my energy on the Nimbus project.

It is now nearly 5 months since the app was feature complete and I haven’t seen it released except for when the project was leaked on Techcrunch. Needless to say this was a frustrating experience for me. The experience of working on this app was a large contribution to the reasons why I left Facebook, though that doesn’t mean it wasn’t a difficult decision.”

Verkoeyen’s move highlights the difficult position Facebook is in with its mobile platform. If it builds on iOS, the company currently can’t earn any downstream revenues from its developer ecosystem since Apple controls payments on its platform. On Android, the platform is controlled by a direct rival Google, which could one day decide to bring in its own social graph through Google+. On both platforms, third-party developers are technically not supposed to build store-like experiences that would sell or distribute other apps.

As a result, Facebook hasn’t articulated what it plans to do on mobile for most of this year. In January, chief technology officer Bret Taylor vaguely stressed that the company’s future is in HTML5. But mobile was scarcely present at last week’s f8 developer conference where just a brief glimpse of the iOS version of Facebook’s new Timeline product was shown. Facebook’s on-off relationship with Apple has also complicated the decision around whether to focus on a native iPad app versus an HTML5-based tablet experience that could come with third-party games and apps. This relationship may have warmed up again in recent months thanks to Android’s momentum, however.

Facebook’s reticence around mobile may also be about change in two to three weeks. We’re not exactly sure on the timing for the launch of a mobile games platform, but we’ve directly heard that it is coming soon.

Mobile game developers are divided over whether Facebook can make a meaningful entrance at this point. The companies that are already financially successful on iOS tend to be skeptical that an HTML5 platform would offer anywhere near the user experience that native apps bring. The developers who have done well on Facebook but have yet to make a serious debut on iOS or Android tend to argue that this project shouldn’t be written off.