Is it possible to simulate transistors using open-source tools only?
How fast are the available solvers?
How hard is it to interface with existing PDKs?
The following talks provide very promising answers:
* ngspice - an open source mixed signal circuit simulator, by Holger Vogt
* Gnu Circuit Analysis Package (GnuCap), by Al Davis
* Converting 45nm transistor netlists to open standards, by Thomas Benz