Incursion 1.1.0 is scheduled to launch tomorrow, Jan. 18, but it looks like a very low number of EVE Online players won't be able to log in due to some CPU changes. Here are the details from a new dev blog entry:

"CPUs that don't support the SSE2 instruction set will not be able to run EVE Online after the Incursion 1.1.0 deployment on Tuesday, January 18, 2011. This will cause players still using Intel Pentium 3 or older and AMD Athlon XP or older CPUs to not be able to run the EVE Online client. Athlon 64 CPUs are not affected."

CCP estimates that around 0.3% of the playerbase will be affected. The number is so low because this generation of CPUs is nearly extinct.