As part of EarthLink's effort to shed enormously costly projects with no near-term return, they aren't putting more money in Helio right now: The mobile virtual network operator (MVNO), which buys minutes and data at wholesale from Sprint (and possibly Verizon), was founded to bring cool South Korean phones and interesting services to youth and young adults in the U.S. It's taken hundreds of millions of dollars to reach a point where it's future isn't well predicted. Few MVNOs make it.
SK Telecom has been EarthLink's 50-50 partner, and EarthLink and Boingo Wireless founder Sky Dayton has headed up the effort. The initial investment was $220m from each firm. SK Telecom just put $270m more into the venture, and IDG News Service reports that it may assume majority ownership, too. If I read the report correctly, EarthLink has put $250m in so far and SK Telecom has now put in $590m.
Helio has just 130,000 subscribers, a tiny drop in the buckets compared to over 100m cell subscribers in the US. They're aiming for 200,000 to 250,000 subscribers by the end of 2007 with revenue of $140m to $170m.