ICM v5.1.1 got released today. To download from Passport Advantage, the package numbers are below:
AIX: CI9VBML
Windows: CI9VDML
RHEL: CI9VCML
Solaris: CI9VEML.
The new ICM Infocenter is also now available.
Also, quite a useful article here that goes through ICM development for CMIS.