Update: no, Ballmer didn't reveal the Xbox 720, although he did announce Kinect on Windows, to come in February. A longer analysis of his CES 2012 keynote speech is available here.

Macworld is in Las Vegas for CES 2012, the annual gathering of consumer electronics developers, distributors, analysts and journalists, and thoughts are turning to tonight's keynote speech from Microsoft's Steve Ballmer.

Microsoft has said that this will be the last CES where it gives a keynote speech - or even holds a booth - because CES's January timeframe doesn't fit in well with the Microsoft product launch calendar.

The buzz here in Vegas is that the old showman Ballmer will want to go out with a bang, and announce something memorable in his final CES keynote.

One theory is that he'll give us some concrete details of the follow-up to the Xbox 360, which is certainly due for an overhaul after being on the market since 2005. And with Nintendo's next-gen Wii U console out in the open, there's pressure on Microsoft and Sony to respond with news about the PS4 and Xbox 720 (or whatever it chooses to call the 'Nextbox').

Going out with a bang, or a whimper?

On the other hand, the reasoning in Microsoft's blog post amounts to an admission that it struggles to come up with exciting product news for its keynotes at CES, and it seems unlikely that this one will be significantly different. And if it was aiming for the 'going out with a bang' approach, surely Microsoft would a) have made more of this being the last one, instead of slipping it out in a blog post, and b) timed that announcement closer to the actual event?

The real showy thing to do is to start stage-managing your own events, like Apple has done so successfully over the years, instead of getting drowned out by the noise of hundreds of other product announcements.

And how many big announcements have emerged from Microsoft keynotes over the years? Hardly any. Last year Ballmer announced some minor upgrades to the Kinect service, but Kinect itself was announced where? E3. That games-focused show seems like a more likely venue for the Xbox 720 reveal.

Although there are sceptics who believe the Xbox 720 will wait even longer than that: our colleague Matt Peckham at PC World reckons the firm would shy away from harming its current (healthy) sales of 360 games, and isn't actually threatened by Nintendo's Wii U.

Most likely focus tonight? Windows 8, and Windows 8 on tablets. After all, this should be an exciting year for Microsoft on the OS front. There might be some hints about the Xbox 720, but I can't imagine there'll be much of substance. I dearly hope to be wrong, however.

Anyway, I'll be reporting from the keynote tonight, at 6.30pm Pacific Time (4.30am Tuesday morning in the UK), so tune into Macworld for the latest announcements.