Hi Linda,
here is the official wording:
BEx 3.5 is part of BW 3.5/SAP NetWeaver 04 and the maintenance cycle is coupled to this release (see SAP note 1410878 - SMP Login required).
BEx 3.5 in BW 7.0x and BW 7.3x will be supported as long as BEx 3.5 (NetWeaver 2004) is in extended Maintenance (2013). Afterwards BEX 3.5 is in customer specific Maintenance. Please note that full PAM support of BEx 3.5 cannot be granted by SAP - as Microsoft has removed, e.g., support for some components
within Windows 7 that had been used by BEx Web Application Designer 3.5.
take a look here:
http://scn.sap.com/community/business-explorer
regards
Ingo Hilgefort, SAP