The number of stations will triple by the end of June, and by the end of 2013, Tesla owners will be able to drive from Los Angeles to New York using the stations.
Tesla also plans to add ports at many stations (so more cars can charge at the same time). The maximum charge rate at the stations will go up by a third, so batteries can be charged to two-thirds capacity in 20 minutes, instead of halfway in 30 minutes.
Here's the network as it stands now. Red dots indicate installed stations, gray dots are stations in progress: