For self launching gliders, where the mission requires relatively much power (in glider terms), but not much energy (just enough to get up into thermals, and then some to get home after you screwed up), electric propulsion beats infernal combustion today (even with regards to aircraft empty weight). HOWEVER, the energy density of today's batteries is two orders of magnitude less than hydrocarbons.
Anybody who projects battery powered airliners in the relatively near future either does not know what he or she is talking about, or has the need for some positive (although gullible) press. (for example, Boeing hyped the Sonic Cruiser when Airbus was about to roll out the A380)
What can be expected is varying degrees of hybridization, where energy production can take place on one location, while the propulsors are distributed where it is aerodyynamically advantageous.
So: Expect battery electric sailplanes, aerobatic machines, initial trainers, and maybe even intra city hoppers to dominate the future. Everything else needs a different energy storage solution.
and Keith.. try to guess what I do for a living :)..