(I think the little cartoon showing the battle of the railway gauges draws a very clever analogy.)
Here's a list of the devices to date :
iRex iLiad - Holland-based firm launched the first e-reader in the UK this month, sold exclusively in Borders. Uses Linux operating systems which allows third-party development. Supports wi-fi.
Formats: XHTML, .pdfs, Mobipocket.
Retail price: £399
Sony Reader Launched in the US in 2006 and a 2.0 version is widely tipped to be released in the UK later this year. Titles can be purchased from Sony's Connect website which has about 40,000 titles. Can play MP3 files.
Formats: BBeB Book, Adobe pdf, Jpegs, can support Microsoft Word with conversion.
Retail price: $299
Amazon Kindle Released last November in the US to much fanfare. Features include wireless connectivity which enables downloads direct to the Kindle without a computer. Currently about 125,000 Kindle titles available from Amazon.com. UK launch TBA.
Formats: Kindle (.azw), can also read non-DRM Mobipocket files.
Retail price: $399
Two to watch
Cybook Gen 3 French firm Bokeen's device launched in the US and France in October 2007. Stores up to 1,000 books and the company promises a 100-day battery life for the casual reader.
Formats: Mobipocket, PalmDoc, HTML, .txt, .pdf.
Retail price: $350
Redius Polymer Vision Spin-off of Dutch electronics giant Philips says it will launch its mobile phone/e-book reader in the UK later this year. The device, the size of a normal mobile phone, has a five-inch "rollable screen".
Formats: TBA. Retail: TBA