[yetfeo]

GHash.io and BTC Guild own >50% between them though: http://blockorigin.pfoe.be/top.php

Eligius have some mining rules which one could regard as not acting in good faith (rejecting gambling site transactions, etc) depending on your point of view. This can prevent some from using them and limits their hashrate somewhat.

If you look at the top pools list compared to 6 months ago that landscape has changed quite a bit. The pools outside of the top 5 have less market share and there are less pools. Mining power is slowly centralizing: https://web.archive.org/web/20130215040845/http://blockorigi...

[nwh]

You're not wrong that there's less pools, I think it's just somewhat due to a lot of miners not understanding how pools work. There's an unfortunate misconception that the size of the pool impacts your income, so they gravitate to the largest pool. Ghash.io is almost certainly evil (attacking sites by double spending in the past), but there's not much we can do about it unfortunately. Hopefully p2pool can eventually become larger and more significant, then the issue goes away somewhat.

[thekiwi99]

Can you provide a source for Ghash.io double spending? I've not heard about that before, and it seems unlikely.

[hendzen]

https://bitcointalk.org/index.php?topic=327767.0

[nwh]

Critically in this thread they do acknowledge the double spends happened.