Mild-moderate dissociation is present in a lot of different psychiatric disorders, including borderline, mood disorders, schizophrenia, etc...

I did a lot of reading on dissociation in BPD a few months ago because I was concerned that I may have been borderline and I do experience a lot of (mild) dissociation. I found that there are differences in brain physiology seen in BPD that make sufferers more likely to experience dissociation. I also found an article thad said that a very high percentage (I want to say 75%?) of people with DID (most severe dissociative disorder) also met the criteria for BPD.

So dissociation and BPD are definitely closely linked.