The pressure is mounting on Windows Mobile, Microsoft's increasingly antiquated mobile operating system.
Last week, Google lifted the lid on world's worst-kept secret and confirmed the existence of Android, a mobile OS of its own.
But it's the Apple iPhone juggernaut that's really putting the squeeze on Windows Mobile. Friday's UK launch of the iPhone drew an enormous rabble of both punters and press, despite the fact that the thing is relatively ancient news. It's been available in the US since June.
But is the iPhone really that much better than your typical Window Mobile-powered smartphone? And if so, what does Microsoft need to do to close the gap?
Age old dichotomy
When it comes to iPhone vs. Windows Mobile, it's the same age old Apple vs. Microsoft dichotomy. It's a contest between peerless usability and polish on the one hand and almost infinite flexibility and configurability on the other.
In that sense, Windows Mobile is identical to full-fat Windows for desktop PCs. It's a completely open platform with a huge ecosystem of supporting third-party software. If you need it or can even think of it, odds are somebody has coded it for Windows Mobile.
But just as it shares many traditional Windows strengths, it's also shot through with the all too familiar failings. Whether it's the clunky interface and piss poor usability or patchy stability and questionable security. It's the same story in Windows Mobile as it is in Windows Major.
And just like Windows on the desktop, if you dig deep enough, you'll find some pretty ancient underpinnings. In the case of Vista, its lineage can be traced back to Windows NT. For Windows Mobile, there are some pretty ripe Windows CE gubbins in there. As with Vista's deceptively snazzy 3D interface, the fancy icons of latest Windows Mobile 6 version won't fool you for long.
OS X all over again
The arrival of the iPhone has only made Windows Mobile's shortcomings all the more obvious. It's had a similar impact to that which Apple's OS X originally had way back in 2001; to instantly show the Windows alternative as utterly antiquated and outmoded.
The iPhone's biggest advantage is its interface. The application that arguably showcases it the best is web browsing.
The iPhone's awesome gesture-controlled Safari web browser is so much better than Windows Mobile's feature-light and maddeningly scroll-intensive build of Internet Explorer, it's not funny. You can't even have more than one web page open at a time in Mobile Internet Explorer, for goodness sake.
Switching between portrait and landscape viewing is a mere flick of the wrist away on the iPhone. On a Windows Mobile device, you'll be battling context menus with that fiddly little pointing stick. Yuck.
Elsewhere, it's a similar story. Whether its navigating contacts or just sending a text message, the iPhone is an infinitely more pleasant mobile companion. Anyone with a touchscreen Windows Mobile Device will be aware of just how ludicrously bad it is for finger prodding operation.
Not a nice gesture
Windows Mobile has absolutely none of the slickness or intuitiveness that you get with an iPhone. The idea of effortless gesture control simply has not entered the Windows interface lexicon.
And yet all is not lost for Windows Mobile users. There are legions of alternatives to the standard, bundled applications. Opera already offers a browser with tabbed browsing, for instance (and it's working on a new version with similar overview and intelligent zoom to Safari on the iPhone).
Similarly, with the right software installed, you can play back a far wider range of video files and codecs on Windows Mobile.
To be fair to Windows Mobile, one must also acknowledge the huge range of handsets it has to cope with. There's tons of choice in terms of hardware. That's in stark contrast to the tightly controlled iPhone and iPod touch platform upon which Apple's cut-down mobile OS X is installed.
Failings and foibles
Ultimately, however, I can't see Microsoft really addressing Windows Mobile's major failings. In recent years, it has shown absolutely no evidence of being able to respond to customer needs in terms of interfaces and usability.
Windows Mobile 6 is already way behind the curve and the next major build, codenamed Photon, isn't even due for a couple of years.
That could be a serious problem for Microsoft. Compared with the effective monopoly it enjoys on the desktop, it's much, much more vulnerable in the mobile sector. If Apple stays true to its word and opens up the iPhone platform to developers, the sky's the limit.
Already, the iPhone is popular enough in the US to encourage wide ranging third party software development. An open-platform iPhone really would offer the best of both worlds.