Definitely blockexplorer. It's down at the moment.

There is a string of 8 invalid blocks made yesterday. I hope they are going to be fixed too.

Slush:  Any reason you don't just poll bitcoind for validity rather than an external website?

This is simple check against Sibil attack. Of course block explorers can be on the same "cluster", but it's harder than isolate just one bitcoind instance. I'm pretty paranoid and system marks block as invalid when there's even chance that something on bitcoin network is broken. Until this issue, blockexplorer had very high uptime so there wasn't any need to solve it in different way. But this week outage is really strange...

I was going to make the same post lool  Yeah, congrats slush!

Hey now, Time Travelling pools were (or will be depending upon your interpretation of temporal interference) banned!  Nothing can stop a 51% attack when you can just send blocks back to the days of CPU mining!

Are there really 8 invalid blocks or is there some kind of problem again?

yeah, slush has been having to validate blocks manually due to the blockexplorer issues.

But he did say that he was going to add blockchain.info to the validation process so the pool can use either one to validate the blocks.  Im guessing he's working on it right now...

wow, 167730 NMC!