I sat in a darkened basement conference room at the Royal Aeronautical Society in Mayfair yesterday morning, listening to some terrific presentations and insights at the Echo Research ‘Fit for the Future 2010’ summit.

Of the more than 100 people in the packed venue, I spotted a couple of them with laptops open. I saw one person with an iPad. The rest, probably a dozen or so mobile devices with a preponderance of Blackberrys.

For my part, I sat very cosily with my Dell Streak. This Android-based mobile device, a hybrid as I see it -  a cross-over between a mobile phone and a tablet computer – is the perfect size and shape to use when sat in a conference like the one I mention to tweet, do email, do whatever you want to do and be discreet about it.

The size of the Streak is ideal (see specs). Smaller than a laptop or an iPad and bigger than a mobile phone, you can sit comfortably with the device in one hand, resting on your knee perhaps, and the other typing away (or, in my case, Swyping away).

The 5-inch screen is pretty good for this type of activity. It’s very easy to hold the device in landscape mode in one hand as you type/Swype with the other. Indeed, this device is designed for doing lots of things with it that don’t involve making or receiving a phone call. It does that, too, but I wouldn’t (and don’t) use it at all as a phone – that SIM card and mobile plan is all about data not voice, where the cellular network connectivity complements wifi and Bluetooth: lots of options to get online or connected.

Yesterday’s experience with the Dell Streak follows casual uses I’ve made of the device on a train, on a bus, in the car stuck in a traffic jam, and of course at my desk in the office. It’s perfect for tweeting, doing email, etc, on the move and especially in  cramped places. I’m actually looking forward to the flight experience where the considerate passenger seated in front of you rams his seat into full recline right after take-off: I bet I have no problem at all using the Streak in that situation!

The only big negative I can note so far is the camera. Yes, it’s 5 megapixels and has a flash, which puts it on a par with my HTC Desire (and, before that, my Nokia N95 8GB). But the pictures it takes aren’t as good as taken with those other devices and the camera app is so slow – by the time it’s readied itself after you press the button, the subject you’re taking the photo of has probably moved. That’s what happened at yesterday’s event, useless photos resulting. Indeed, the pics you see in this post were all taken with the HTC Desire. That said, TechRadar rates the camera highly in their review.

And of course, there’s the operating system itself: Android 1.6, an earlier version that doesn’t provide support for the latest generation of smart apps. If there’s one thing I wish Dell would do immediately is release Android 2.2 for the Dell Streak. How about it, Dell? When’s an official version coming, not a hack?

In any event, I like my Dell Streak, not for taking photos but for using apps like Twitter and in situations like I experienced yesterday. No need to lug the laptop.

So where is the Dell Streak positioned? Is it a phone or is it a tablet? Those are the wrong questions, in my view: you should be asking how you’d use it. For me yesterday, it was a perfect tool for discreet tweets.

And just wait until you see the 7-inch screen version coming next year. And the rumoured 10-inch screen…