You're all caught up! [closed]
Solution 1:
It means that what you know, what you've read, or what you've done is everything that's currently available to know, read, do, etcetera.
In the case of social sites like Wordpress or Google+, it probably means you've read all the most recent updates that your contacts posted and there's nothing else to read until they post more.
The third definition here emphasizes "belatedness" as part of the meaning (that is, reading or learning something belatedly), but that depends on usage context.