A lot of anomalies in the Google SERPs have been spotted by the members of WebmasterWorld recently!
"I'm seeing some index pages disappear (no longer showing on site: command or within the visible serps for vanity.domain searches) that were previously filtered 4-7 pages deep due to the dupe meta descriptions; this is happening at approximately 2 months post the issue arrising, so I'm curious whether some data is being folded pretty heavily right now. If anyone else sees a major page disappear over the next couple of days, just breathe and wait a bit…it'll probably come back if you weren't doing anything too egregious."
Some net users are finding millions of search results on typing a particular keyword. For example, a search is performed in the afternoon, and it generates 1 million search results. The same search is conducted at night, and almost 2 million search results are found at the later part of the day!
This can be due to the querying different datacenters!
You can try searching different datacenters at PageTraffic's Google Datacenter Search Tool.