Your confusion is understandable. OS2008 on the N800 started with people shoehorning the N810's OS into the N800. That took a Linux flasher as Nokia hadn't intended for people to do it. However, from there discussions of OS2008 in these forums blended smoothly into talk of the OS2008 beta for the N800.

Since the OS2008 beta for the N800 is an official release, it doesn't require a Linux flasher, standing on one foot, or sacrificial chickens. (Though there are those who still prefer them.) If you missed a thread or two though, you missed that discussion. Easy enough to do. And, as there's a mix of folks using the beta and folks still using the N810's shoehorned OS, it's often unclear precisely what OS2008 a N800-owning poster is using.

Anyway, have fun with your new OS, and may Nokia not frustrate you by releasing the OS2008 final version two minutes after you finish reinstalling all your applications.