After several years of playing catch-up to rivals, Nokia today came up with its first Windows Phone, a long-awaited gizmo that finally looks the part and which could resurrect the Finnish giant’s ailing smartphone business.

The Lumia 800, unveiled at its annual Nokia World conference, comes with all the bells and whistles expected today – a 3.7-inch AMOLED screen, 1.4GHz processor and an 8-meg Carl-Zeiss lens, for starters.

Notably, there’s no SD card slot, so the 16GB onboard will have to do for your apps, movies, songs and pictures. The good news for music lovers is that it supports FLAC natively, so you can play back your high-res music tracks without having to convert them to MP3s.

As expected, the Lumia 800 looks identical to the N9 first shown at CommunicAsia in June. The main difference is that it runs Microsoft’s much-heralded Windows Phone 7.5 “Mango” operating system, which has more apps available than the N9′s Meego OS. The design has wowed critics with a unique curved glass screen, which seems to float like a “pillow” on the main frame.

So the Lumia 800 has a massively improved OS, which now contends well with Android and iPhone devices, and it is backed by a good-looking design. Is this the return that Nokia has hinted at all these months, after hitting rock bottom earlier this year? …

Microsoft has sent its next iteration of the Windows Phone software to handset makers, as it wraps up the operating system’s features and software code ahead of a launch in Fall 2011.

The so-called Mango update, unveiled two months ago, promises a number of fixes and updates to the original Windows Phone, which looked great when launched late last year but had an uphill struggle taking on Google’s Android and Apple’s iOS devices. …