Techcrunch reported that, SK Telecom announced it will invest another $270m in Helio, which is expected to lose $340-$360m this year on a revenue of $140-170m.
With other MVNOs like ESPN mobile and Amp'd mobile busted, SK Telecom's move looks a bit dicey. But SK Telecom's mission seems to go beyond the boundary of the smallish Korean market. SKT also invested $1 bn for 6.6% stake in China Unicom (#2 Chinese mobile service provider) last June.
By the way, I found something interesting on the Wikipedia entry on SK Telecom, that the company kicks out people over 45:
At 45 years old the employee must leave the company and accept SKT's retirement package OR join SKT's "Manpower Surplus team" and continue to receive a salary but usually the shame of just sitting at a desk and doing nothing and the loss of retirement benefits is enough to make most employees leave.
This sounds pretty much true, but it was put pretty bluntly - especially given it's on the Wiki.