Bungie writer Joseph Staten has said to OXM (via CVG) that Halo 3: ODST has connections to the upcoming Halo: Reach.
“The Halo Universe has always had these interconnections but when we made ODST we had the luxury of knowing the Halo game we were going to make next. So it made a lot of sense to us to put those kind of connections in,” said Staten.
He also admitted that although ODST character Buck is a vet of the events on Reach, he isn’t sure if he will appear in the next Halo title.
“Buck has very specific lines about what he witnessed on planet Reach and we absolutely wanted to telegraph some of that stuff. Whether or not he’s going to show up in Halo Reach we’re not talking about / have no idea.”
More through the link.