tell application "ecto"
set theDocument to document 1
set theTitle to entry title of theDocument
set theBody to entry body of theDocument
set theCrossPost to make new document at beginning of documents with properties {current personality:"ecto account name", current blog:"blog title", entry title:theTitle, entry body:theBody, publish status:true, categories:{}}
set current blog of theCrossPost to "blog title"
end tell
This is pretty easy to read code, so I left off the comments. The only odd part is this line:
set current blog of theCrossPost to "blog title"
Which is necessitated by ecto's suboptimal blog listing facility. (It lists "personalities" and blogs as colon delimited text in one big string, with one line per entry. So no matter what initial blog you set it to, it's always going to pick the first one by default. So you have to re-set the actual blog. Annoying.) However, this is still better than manual copy and paste. I did post some of the issues with ecto's dictionary in the ecto forums, so we'll see what happens.