As was pointed out by Xenomrph in a different topic, the Timeline that has been posted on the Weyland Industries page doesn't actually state when the company was founded, and while Peter is referred to as the founder elsewhere it is a bit more unclear in the Timeline.
The Timeline does in fact, upon further inspection, seem to be going out of its way to accommodate the other films, and some of the games, even in subtle ways.
The penal colonies from Alien 3.
The Marines, Power Loaders, the Holographic Jungle thingy Ripley was sitting in, Archeron (yes I spelled that correctly, go check the site) being the name of LV-426, and more from Aliens.
Yutani Corporation is first (and only) mentioned at 2029, which is one year before Predator Concrete Jungle, in which they begin talks of some sort of partnership with Weyland Industries.
The date of AvP is in the timeline, given as the date of Peter's twelfth patent, which is not otherwise significant unless you take the date into account.
Quote from: predxeno on Mar 18, 2012, 10:59:12 PM
Yeah, and the mention of Weyland Industries winning a patent against the Yutani Corporation happened only 1 year before the 2 companies merged in Predator Concrete Jungle.
They don't actually merge in CJ. Yutani proposes they begin looking into some form of partnership. This makes more sense given that they just lost the lawsuit the year before.