If you are wanting to know what SAP enhancement pack you are running on your SAP system it's quite simple if you know where to look.
Goto Transaction SPAM
In the Directory Frame (bottom left)
Select Imported Support Packages
Scroll down to and expand the component "SAP_AP"
SAP_AP 700 -> EHP0
SAP_AP 701 -> EHP1
SAP_AP 702 -> EHP2
SAP_AP 703 -> EHP3
SAP_AP 704 -> EHP4
SAP_AP_705 -> EHP5
Support Package number gives you the support pack you are on for that enhancement. ie EHP 0 Support Pack 22 is:
SAPKNA7022 SAP_AP 700: Support Package 0022 Imported on 01.04.2012 at 11:52:20