Mozilla has ceased development of the upcoming Windows Mobile version of its web browser, Firefox, currently the second most popular desktop browser on earth.

Unfortunately, it seems we won't be seeing Firefox on the nice Windows Phone 7 display

The word from the folks at Mozilla won’t come as a surprise to any who had followed the company’s opening of an exchange with Microsoft earlier in the week, with Firefox’s Rob Sayre writing an open letter to Microsoft CEO Steve Ballmer questioning the lack of a native development kit (NDK) to go alongside the software development kit (SDK) for Microsoft’s upcoming refresh to its mobile line, Windows Phone 7. If nothing else, the tone of the open letter indicated a certain dissatisfaction with Microsoft’s closed-platform approach to mobile development.

Now though, it seems that things have gone that bit further, with Mozilla announcing in a blog posting that it will be axing the Windows Phone 7 version of Firefox entirely.

The word from Mozilla is that it’s been working on a version of Firefox for Windows Mobile for quite a while, expecting Microsoft to ‘double down’ in the mobile market with the move to Windows Phone 7. Unfortunately, after praising Windows Phone 7, the post takes a fairly sharp turn, saying that,

“While we think Windows Phone 7 looks interesting and has the potential to do well in the market, Microsoft has unfortunately decided to close off development to native applications. Because of this, we won’t be able to provide Firefox for Windows Phone 7 at this time.”

If nothing else, this is bad news for any Firefox fans with an interest in Windows Phone 7. Still, it’ll be interesting to see what this turns up, given the generally litigious nature of the browser space. Between this and Opera submitting a browser to Apple’s App Store, the mobile browser space could be in for a bit of a shakeup.