I got PR5 for a new site that missed the last PR update too.
It is quite strange, but G sxeems to have rewarded new internal pages of established sites with big PR boosts and forgotten about updating their homepages…
In the grand scheme of things i think it means nothing really…only that other people might be more eager to link to you and it may reflect positively in that manner.
But as regards SERPS it has no effect on its on.