Aloha, Ryan! Thanks for spreading the news. I wanted to get it out there pretty quick as I thought a lot of folk would definitely be in for the "secret" BB bonus disc if they knew about it!
Oh boy! We know from the unboxing videos online that the bonus disc in the Complete Collection set has a nice pattern on it. The DVD with all the bonus content that comes with the BB blu-ray is a plain jane grey DVD that says its series six bonus - so its not just a matter of mistakingly...
I've just got back from buying Lost Season 6 (blu-ray) at Best Buy. This comes with an extra slipcover that contains a bonus disc. As has been noted by other folks, the bonus disc that came with my blu-ray set was actually a DVD that seems to be the extra disc from the Complete...