A number of manufactured launched Windows RT tablets, but all of those, save Microsoft, have bailed. Aside from Dell, there are also Lenovo, Asus, and Samsung who have halted Windows RT device development. According to reports, HTC cancelled its plans for a larger-screened Windows RT tablet, and no manufacturers opted to announce a Windows RT device during Computex, recently.
There is the rumored Lumia 2520 tablet which is expected to launch at an event in October, but since Microsoft has acquired Nokia's devices and services business, this isn't really any different that Microsoft itself backing RT, right?
You got the big picture: Right now, Windows RT is out of favor with anyone except its own developer / manufacturer.
Windows RT tablets haven't been popular for a lot of reasons, including pricing, but also because RT will not run anything but Metro-style apps. Notably, once Microsoft lowered the price of the original Surface RT tablet, it saw a spike in sales.
Microsoft unveiled its latest Surface RT tablet, dubbed Surface 2 and running Windows RT 8.1 on top of an NVIDIA Tegra 4 system-on-a-chip (SOC), on Monday. It will be priced slightly lower than the original Surface RT's price, at $449, while the original will still sell at $349.
At the same time, it also unveiled the successor to its more successful (but modestly so) Windows 8 tablet, the Surface Pro 2. The original Surface Pro will continue to sell at $799 (the price to which it was recently cut), with the new tablet selling at the original price of $899 (and up).
Microsoft has addressed the battery issues in the Surface Pro with the 2, with a Haswell power-sipping CPU and an (unfortunately, not coming until early 2014) Power Cover which includes a keyboard and a battery.