RHEL provides a stable kernel ABI. "Once a symbol has been introduced into the Kernel Application Binary Interface (kABI) for a particular major release of Red Hat Enterprise Linux it will not be removed, nor will its meaning be changed during that kernel major release's complete life cycle." SLES is another distribution with a stable kernel ABI.
Additionally, in practice a module (driver) that ignores the kABI will usually work for all patched kernel versions on a given minor release (~service pack). e.g. A minor release 6.X introduces a new kernel X' (2.6.32-X'.Y) and a module built against X'-0 will work for all Y.