If you have hardware in which the sampling rate can be manually changed (Pro Tools) it is possible to have a playback "speed" slower or faster. Say you recorded an audio file at 48khz, bounced it to a file with a setting of 44.1, then imported it back to the original project (which would still have hardware clocked at 48khz), it would playback faster - and thus - shorter.
Most hardware devices will automatically detect the sampling rate and set the playback rate accordingly.
Primary System Info
Mac Pro 2x3.2 Quadcore - 10.5.3 - QT 7.4.5 - 6MBram - nvidia8800GT - SATA internal & external storage - Blackmagic Multibridge Pro (v6.7)- Open GL 1.5.6 - Wacom Intous2 tablet