A late afternoon in the US update with more authoritative information:
There are actually 2 speculative execution flaws in at least Intel, if not ARM and AMD processors:
1. Meltdown - breaks kernel memory isolation from user programs
- general fixes in OS updates imminent (with workload-specific performance impacts)
2. Spectre - breaks user program 1 memory isolation from user program 2
- specific fixes possible, processor design enhancements needed
Papers on each are available at:
https://meltdownattack.com/Mark