What is this element on the far right of schematic described as "270 OHM"? Is this some kind of inductor? What is its purpose in this device (this is a reference design of dc-dc power supply of sim900 taken from its datasheet) and what would be an exemplary part number?
It is a ferrite bead with a 270Ω impedance.
Ferrite beads have a number of symbols in use in schematics. There hasn't been a standardization in the symbol like for other components. Many people treat them like a simple inductor, some like a resistor, some with a special symbol they made for it. Some of the symbols seen include:
It's most likely a ferrite bead for high-frequency suppression, given the fact that the SIM900 you described seems to be a GSM/GPRS phone module doohickey which is likely very sensitive to HF noise.
(Also, the schematic symbol implies 'inductor with something other than an air core'.)
The 270 ohm figure is almost certainly the peak impedance of the bead at its target frequency.