The current stable version of svgalib is 1.3.0, released on 12 July 1998.
It is available from many popular Linux ftp sites such as
sunsite.unc.edu and
tsx-11.mit.edu.
No new development snapshots have been released so far.
There is not currently a centralized location for such patches, so as I find them I will link to them here:
(Note that at this time there are no development snapshots! However there may be some again in the future so this section remains.)
Development snapshots of svgalib are currently made available directly only to those who are actively participating in the development of svgalib. Many of the new features, especially the new display drivers, are somewhat buggy and unstable, so you should be willing and able to help debug any problems you find - which makes you a developer.
Note that some new features are also available as patches against the stable release, such as improved IntelliMouse/MouseMan+ support.
At this time there is no difference since a new stable release was just made.