In theory, LTE is capable of delivering mobile broadband with connection speeds of up to 1 Gbps, but this requires 4G. Connection speeds of 150 Mbps is even possible, but this still depends on the capacity of the network.
But currently, mobile broadband providers claim speeds of up to 7.2 Mbps and with HSPA this could be as high as 14.4 Mbps. Yet in the real world user of mobile broadband are experiencing connection speeds of between 1 Mbps and 2 Mbps.
LTE could speed things up, but with the issues concerning the spectrum, delays are likely to mean that any LTE roll out will not start until the end of 2011.