It is an instruction to Google search to look for "anchor text" containing the search phrase which follows the allinanchor: For example, allinanchor:bodyboard shop will look for URLs which contain "bodyboard shop" as the anchor text. See http://www.bandofgonzos.com/phpbb/viewtopic.php?t=401 for more information on this and other Google advanced search operators.
Just curious to see if other people are seeing what I think is inaccurate or perhaps delayed rankings when using the allinanchor command. I have a keyword that I was targeting prior to the Dec google shakeup: "blue widgets". I was actually number 1 (allinanchor) just using the coop as the primary bl source. I dropped using the coop for that keyword since it dropped in the serps and never recovered and diverted it to another keyword. This was around Christmas time. I just checked today and my allinanchor is still number 5. I would have thought it would have dropped off much more than that. So, it this usual? I had always thought that the allinanchor was usually accurate and up-to-date.
Some times it is and sometimes it isn't but it is worth keeping in mind that no one outside of the Googleplex knows how the results are ranked for an allinanchor: search. - Michael
You may drop in allinchor: if your cometition get more links or more quality anchor links. And I gues, if google discard some of links to you or lower the PR of some pages linking to you.