We report an all-fiber polarization switch made out of silica-based microstructured fiber suitable for Q-switching all-fiber lasers. Nanosecond high-voltage pulses are used to heat and expand an internal electrode to cause lambda/2-polarization rotation in less than 10 ns for 1.5 microm light. The 10 cm long component has an experimentally measured optical insertion loss of 0.2 dB and a 0-10 kHz repetition frequency capacity and has been durability tested for more than 10(9) pulses.