from http://www.novell.com/docrep/2012/01/sle11_sp2_isv_faq.pdf :
"How will SUSE maintain compatibility between SUSE Linux Enterprise 11 SP1 and SP2?
Compatibility will be delivered by maintaining runtime library interface compatibility. SUSE will ensure that user-
space interfaces will not change between SUSE Linux Enterprise 11 SP1 and SP2. ISV certifications issued for
software running on SUSE Linux Enterprise 11 should remain valid for SP2. With regard to the kernel, we are taking
all steps necessary to ensure full compatibility of the kernel’s interfaces to user-space libraries and applications, and
we are working closely with ISVs around their needs in this area. For example, the kernel header files (i.e. the
kernel programming interface presented to the compiler) remain at the version used in SUSE Linux Enterprise 11
SP1 except for the addition of newly supported system calls."