Most sites use cookies and have done for years, I believe PPrune does to remove the need to log in each time you visit.
A lot of sites have just put up notices like this to provide butt cover with respect to recently enacted EU data protection / privacy directives - the are not gathering any more info but just telling you what they have done for years.
Most of them are using a standard bit of legalease that covers a lot just in case, but which bears littel relation to what they actually collect or actually do with what they collect.
The comments about third parties in the blurb here do point to a bit more than the basics of adding user convenience and repeat visit counting though. Might be interesting to have a look at who the third parties are and what they do.
Memetic.