It depends... you will have to check for each specific model.

Here's a good general list for different brands and models (mostly electric): http://en.wikipedia.org/wiki/Scale_%28string_instruments%29

For Gibson acoustics, the best way is to go to the Gibson website and check the Specs for each model.

http://www2.gibson.com/Products/Acoustic-Instruments.aspx

For example, the Gibson J-45 Standard has a scale length of 24-3/4".

http://www2.gibson.com/Products/Acoustic-Instruments/Round-Shoulder/Gibson-Acoustic/J-45-Standard/Specs.aspx