If you think a limited range electric vehicle would be a poor choice for a taxi you would be wrong. Very wrong. Taxis are one of the best places to apply electric vehicles right now.
The average NYC taxi drives 180 miles in a 12 hour shift.
The EPA combined driving cycle averages under 30mph with all the stop and go for traffic. So the average taxi probably sits for around 6 hours a day.
A 200 mile range EV would be able to cover the distance of an average NYC taxi. Thats average, you also need to be able to cover the extremes.
If you add in a handful of charging stations where taxis loiter and charging at taxi stands at the airports, train stations, or other major locations the range is greatly extended.
If the taxi spends 2 of its 6 sitting hours at a charging station that can extend the range by over 100 miles ( using a 240V 60A fast charger ).
If it spends 4 of those 6 hours at a charging station that extends the range by over 200 miles. It would be very difficult for the taxi to cover more than 400 miles in the other 8 hours of the 12 hour shift.
Taxi companies may find it compelling to install charging better than 240V 60A that can charge faster.
Taxis already have central dispatching, scheduling in charging time is a trivial addition to that system, the scheduler can easily know where all the taxis are, which charging stations are available and which taxis need charging.
A Nissan Leaf is a $30,000 ( ballpark ) vehicle. Another 100 miles worth of LiFePo4 batteries to increase the range to 200 miles would be around $10000.
A car that drives 180 miles a day, for 365 days a year covers 65700 miles. At $3 a gallon in a 30mpg car thats $6570. At $4 a gallon its $8760. At $5 a gallon its $10950.
The extra cost of the electric car over a gas car will pay for itself in only a couple of years.
The savings in gas would pay for the entire car in around 5 years at probable gas prices ( probable meaning $4 a gallon within 2 years and at least $5 a gallon in 5 years ).
High Speed Charging 
I saw a talk at Ignite a month or so ago about NYC taxicabs. It seems that durability is a big factor there. Attempts to use various more fuel-efficient models have resulted in the taxis wearing out much more quickly than the crown victorias that are the staple taxicab. It’s certainly possible to manufacture an electric car that can handle the wear and tear, but I doubt any off the shelf model would work.
Here are the slides from that talk. If the video shows up at some point I’ll point it out to you: http://gregoryheller.com/node/2009
Ignite Seattle just posted the video from that talk: http://www.igniteseattle.com/2009/11/what-makes-the-greenest-cab-gregory-heller/
Great timing!