Logitech has announced two thin cases for the iPad mini, one of which features a built-in Bluetooth keyboard. Both are ultra-compact to keep the mini as mobile and lightweight as possible while adding dual-layers of protection.
The Ultrathin Keyboard Folio for iPad Mini is the thinnest and lightest keyboard folio from Logitech at 19.3mm thick and 285g. Despite the slimness it manages to cram in standard sized keys, two-sided water-repellent protection, a dual-view stand, and a three-month battery life (based on two hours use a day) that's USB rechargeable. It's available now in the UK in black or green and costs £70.
The Folio Protective Case for iPad Mini offers the same water-repellent protection with stand mode but at just 14mm thick and 196g. Pick one up in pink, yellow, blue or black for £40.
If a more seamless keyboard case is what you're after, the Logitech FabricSkin Keyboard Folio for iPad may be just the thing you're looking for.