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On Tech Brief today: Why the iPad is wacky, spam-sending Linux-lovers, power slides by robots and peripherals big enough to rest your bike against.

• Privacy and - the site has gone through so many twists, turns and reverses that it can be hard to work out what is shared and what is not. Wonder no more. . That's pretty as in worrying, but only if you do nothing about it. Says Mr McKeon:

"I like Facebook. It's helped me reconnect with dozens of people with whom I'd lost touch, and I admire the work their team does. I hope your takeaway from this infographic isn't 'I'm deleting my account'; rather, I hope it's 'I'm checking my privacy settings right now, and changing them to a level with which I'm comfortable'."

• Linux users and Apple fanboys have one thing in common, their disdain for the security shortcomings of Windows. And yet, says , . This is despite Windows having a 92%+ share of the operating system market and Linux only 1.02%.

"By calculating a ratio of spam from a given operating system compared to the market share, we can get a 'spam index', which shows -- relative to its market share -- the likelihood that a particular computer is sending spam, based on its operating system. The resulting calculation gave Linux a 'spam index' of 4.99, compared with an index of 1.01 for Windows."

• More numbers likely to spark debate from which claims that smartphones running Google's Android software outsold the iPhone in the first quarter of 2010. Sales for the quarter put Android on 28%, iPhone on 21% and Blackberry out in front on 36%. NPD tips the hat to the Droid and Droid Eris as the handsets behind the uptick. .

"The continued popularity of messaging phones and smartphones resulted in slightly higher prices for all mobile phones, despite an overall drop in the number of mobile phones purchased in the first quarter. The average selling price for all mobile phones in Q1 reached $88 (£60), which is a 5% increase from Q1 2009. Smartphone unit prices, by comparison, averaged $151 (£201) in Q1 2010, which is a 3% decrease over the previous year."

• Apple's iPad may be selling well, but one man stands aloof from the hullaballoo - . Giving his thoughts on its usability he calls it "weird", "inconsistent" and describes the interface as a "wacky". .

"The first crop of iPad user apps revived memories of Web designs from 1993, when Mosaic first introduced the image map that made it possible for any part of any picture to become a UI element. As a result, graphic designers went wild: anything they could draw could be a UI, whether it made sense or not. It's the same with iPad apps: anything you can show and touch can be a UI on this device. There are no standards and no expectations."

The more he sees, the less he likes. iPad fans should look away now.

"For the last 15 years of Web usability research, the main problems have been that users don't know where to go or which option to choose -- not that they don't even know which options exist. With iPad UIs, we're back to this square one."

• Autonomous vehicles are usually pretty careful drivers. But researchers at Stanford have developed a system that lets a robot car power slide into a parking space. There's even video. It still needs refinement though as the margin of error is two feet. Like a glove? Not quite.

It's not just a cool stunt--this research should give autonomous cars greater flexibility to deal with unexpected situations.

• Finally one for the hardcore geeks. A user manual for a Cray-1 computer - the granddaddy of supercomputers - that dates from 1977. Powered by a 150 KW generator it was capable, brace yourself, of about 160 megaflops. That's 160 million floating point operations (sums) per second. It's .

"Two 20-ton compressors are located external to the computer room to complete the cooling system."

The relentless pace of chip development put that much processing power in a smartphone a long time ago.

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