The existance of www.ericaalbright.com not withstanding, the name of the girl portrayed as "Erica Albright" in the film was certainly not "Erica Albright". Sorkin basically admits to this in a few interviews, where he claims to have changed three specific names and that Erica's was one of those. The person who most fits that character's depiction is a girl names Jessica Alona, but literally all anyone knows about her publicly is that Zuckerberg insulted her on LiveJournal in a drunken rant that seems to have been the start of FaceMash. The actual LiveJournal post is still available, and you can clearly see the original name in the source code for the famous "bitch" post:
Note that this directly contradicts the statements made on the Erica Albright web site, which suggests that either 1) that's a fake web page, or 2) Jessica Alona has decided to go with Sorkin's pseudonym to maintain her own identity.
According to the slashfilm article, as of late 2010, no one named Jessica Alona had come forward to identify herself as the subject of that particular blog post. Also, nothing in that post necessarily claims that Zuckerberg was dating Mrs. Alona, merely that she had somehow angered him, but that does seem most likely. Note that he did not begin dating his current wife until after Facebook was already up and running, which would likely have been years after any possible relationship with the girl that inspired Facebook in the first place.