One of the things I have been most impressed by about Korean mobile comms has been the prevalence of good in-building coverage solutions. Perhaps unsurprisingly, the metro in Seoul has what appears to be ubiquitous coverage (not that unusual - many cities are doing this, using many different technologies, although London will take years )
However, the thing which really caught my eye was the small KTF-branded repeater dangling from the ceiling by a cable, in a small downstairs bar in Seoul. (I think it was one of these , but unfortunately I didn't have a camera with me at the time). Nothing flashy, not even a large venue with 1000s of people (I reckon there could have been a max of 150 in the venue at any one time). Just a pragmatic installation to help people make calls where they want.
I keep hearing stories that European operators are going to be much more aggressive with these types of self-install solutions to improve coverage in retail or public facilities, but I see precious little action. I'm not sure whether there are clear technical or regulatory reasons for this, or whether it's just down to apathy or business model uncertainty. And although I'm hearing a lot more "chatter" about mass deployments of picocells and residential-grade "femtocells", offering extra base station coverage (and extra capacity), I'm pretty sure the time horizons are quite far out.