Is almost everyone messing with timestamps, now?

[Kluge]

The image below is from blockchain.info showing blocks and when they were solved. The numbers are in line with what my client reported. Nothing for 30m, then suddenly, 4 blocks. There's another set of 4 blocks solved within 4 minutes of each other (with non-aligning timestamps) right behind the first set. Is this a freak coincidence, or is there a significant number of miners manipulating timestamps for some reason - or something else?

[organofcorti]

How could they manipulate timestamps?

[Maged]

This is extremely easily to check, thanks to the "Received Time" feature on Blockchain.info. Comparing that with the block's recorded timestamp, you'll notice that the block timestamps were all fairly accurate. The block timestamp is allowed to be off a bit, but Blockchain.info's Received Time is always accurate, assuming the site was online at the time the block was released.