What hack is this? (links on top)

[slappy]

It's part of the "Welcome Messages" in the Welcome Header System.

Go the AdminCP -> vbulletin Options -> Welcome Header System -> Enable Welcome Headers -> Yes

Then enable the features you want to use.

Further down in the Option page you can look at and edit the Phrases in the various circumstances. In this case, it's Enable Post More Often Message. There's a link to get to the Phrase directly and, after you open the edit box, if you click on Copy Default Text, it will put the default text in the editbox and you can change it to your heart's content.

Regards,