343industries Franchise Development Director Frank O'Connor (Stinkles) just confirmed on NeoGAF that the reported 8GB required to play Halo 4 online INCLUDES the episodic downloads of Spartan Ops.
An update on Xbox.com reveals that running Halo 4 multiplayer will require a minimum of 8GB storage on either a Hard Drive or Flash Drive. It's not clear whether this will be required for basic "War Games" multiplayer or if the 8GB is the size of the total Spartan Ops DLC. I'd assume they wouldn't expect you to reserve 8GB for multiplayer and then a further nGB for Spartan Ops content.
Anyone with a Core, Arcade or other low storage version of the 360 may want to think about upgrading their storage.
A 16GB Xbox Flash Drive is available for about £20:
Amazon - 16GB Xbox Flash Drive
A 320GB Hard Drive for the 360 S is available for under £65 and includes a digital copy of Lego Star Wars:
Amazon - 320 GB Xbox 360 Hard Drive
A 60GB Hard Drive for the old style 360 can be picked up for under £20:
Amazon - 60GB Xbox 360 Hard Drive
- Cowboy Out.