BTCMine did a software upgrade and apparently the JSON interface they had is not being consumed by Bitcoin Watch (or the interface changed) ... not sure whether Bitcoin Watch needs to do something or BTCMine does, I suspect the former. That accounts for a pie slice a little larger than BTC Guild.
A bit smaller than BTC Guild actually
The point is still valid though, some pools have been attacked/had downtime lately, which removes them from the pie chart temporarily. Reloading bitcoinwatch's pie chart right now shows Other roughly the size of BTC Guild / BTCMine.
Deepbit is and has been up for awhile at well over 1TH/s, but they were not represented on the pie chart and thus were lumped in with other. The chart is NOT wildly inaccurate and in fact it is precisely accurate [as of the time sample they use to generate the chart anyway]. But, if they aren't consuming the JSON data or the JSON data is not available from a pool, then the processing power generated by pools not represented falls under "other". What would you expect them to put there? I see deepbit is back there now and "other" is precisely reduced accordingly.
Let's get real and let this thread die a timely death.