Very strange but Google have updated their toolbar page rank for the second month in the row. We see about 3 - 4 updates per year usually (although this has slowed over the past year) so odd to see 2 quick updates which I think reflects a problem in the first June update.
Twitter was downgraded to PR0 and Google.com from PR10 to PR9 - the July update rectifies that and returns the original PR to both sites. Our site has remained the same but 2 competitors of mine have dropped pr from PR6 to PR5 and PR4 to PR3, also, NetFrog has been downgraded from PR3 - PR2 which is a shame but of no consequence.
It seems to me that Google must have had a problem with the first update, probably just an anomoly of timing (bad timing whilst algos were doing something odd)