The option to set life time throttling is a vendor configurable option. The vendor has four options:
1 year warranty
3 year warranty
OCZ drives tested to date have been set to 1 year. Mushin and Corsair drives that have been tested have no throttling. Throttling is based on power on hours not calendar hours. A 5 year setting would result in more aggressive throttling than a 1 year setting.
Intel (unlike other vendors) have been given much wider access to customise the Sandforce firmware, but no one knows yet if Intel have selected to use this feature. It will be known soon however as it is currently being tested
I have seen write speeds drop to 6 MB/s after throttling has kicked in. The only way to remove throttling is idle time. As Intel drives are popular in semi enterprise applications I doubt it has been enabled. If it has anyone using the 520 for an onerous enterpise workload is in for a surprise.