Hi Solaris,
Can you please provide the link to the Columbia 2008 thread? I can't find it and I'm curious to see last year's timeline for Early Decision interview invites. You said that some invites were issued only 14 days after review but this is faster than reported in the BW forums... I wouldn't rule it out though. I'm guessing those who heard in only 14 days were probably re-applicants.
Also, the info that Columbia issues interview invites after 2 rounds of review is inaccurate. The Adcom has gone on record several times to point out that the interview invite can be issued at any point in the review process (they usually answer this to alleviate the anxiety of applicants who have not received invites while others who went under review at the same time did). Either the first reviewer or second reviewer can request an interview. Thus the process for those who receive an interview can take 1 of 2 forms, as outlined by Ben May from the Adcom on a previous year's Columbia BW thread:
Submitted > Under Review > 1st Reviewer > Interview Invite > Interview > Application Complete (aka Feedback Submitted) > 2nd Reviewer > Committee Review > Decision
or
Submitted > Under Review > 1st Reviewer > 2nd Reviewer > Interview Invite > Interview > Application Complete (aka Feedback Submitted) > Committee Review > Decision
Hope this clarification helps!