crobb305 - 5:31 am on Apr 7, 2011 (gmt 0)
bramley, I do see what you do. for example, there was a page that ranked high for "blue widget" and "blue widget alternatives". Now I do see the page retaining its rank for "blue widget alternatives" while moving to page 2 for "blue widget". I noticed these for a few other pages too.
I've been watching this phrase-based ranking for a few weeks. My site fell to page 55 for "blue widgets" but I rank #3 with four sitelinks for "big blue widget" (singular), and on page 4 for "big blue widgets" plural. Incidentally, the top 3 ranking for the singular form is new, just since yesterday. Plural forms are hardest hit for me. Traffic is up though.