I'm stumped as to how to prove the provenance of the claimed fake memo with the information that is publically available, and I haven't seen anything that is completely convincing (including Megan McCardle's textual analysis, which has insights, but, as she notes, is not definitive), so I thought I'd put up a timeline in case anyone sees any connections I've missed. I'll update this based on corrections, clarifications, or new information in the comments. All times in Eastern Standard Time, with noted qualifications.
12:13 pm (time zone?) - leaker's email to Desmogblog, etc (per Keith Kloor)
2:13 (time zone?) - Desmogblog's first post (14:13)
3:03 pm - Brad Johnson's first tweet on the subject
3:10 pm - Brad Johnson't first blog post at ThinkProgress Green
3:58 pm - Brendan DeMelle's tweet (1:58 pm PST?)
10:30 pm EST - Suzanne Goldenberg article in The Guardian
1:07 pm - Anthony Watts first writes about the Heartland Leak, confirming he was to receive funding from the Heartland Institute (post not timestamped, but first comment was at 10:07 am PST)
6:03 am Sydney, Australia time(?) - Sydney Morning Herald publishes an article where Robert Carter "did not deny he was being paid by The Heartland Institute, but would not confirm the amount, or if the think tank expected anything in return for its money."
2:30 pm - Heartland Institute reaction (time based on Anthony Watts update on this post)