I just tried to reply to post with the surface and the keyboard came up for a second and then went again. However if I went to another first and then to the reply text box the keyboard stayed on. Very odd and utterly ironic of course.
Interesting. Not sure what other setting can be effecting this. Choosing the Enhanced interface cured the issue for me. I typically browse the forum on my Surface while sitting in the couch without my touch cover. I'll have to look a little more and see if I can sort out what else might be causing it.
This isn't just the RT version of the IE, but the Modern UI version of IE. I have Windows 8 on a PC and have the same problem running from Start IE and Desktop IE is fine. Honestly I really don't like the Modern UI IE, it seems to be a very confused app.