First, save this script on your Mac. Make sure you have installed Growl.
Then schedule it, for instance with Quickeys - I run this script every 20 minutes.
tell application "GrowlHelperApp"
set the allNotificationsList to {"New RSS posts notification"}
set the enabledNotificationsList to {"New RSS posts notification"}
register as application ¬
"New feed posts notifier" all notifications allNotificationsList ¬
default notifications enabledNotificationsList ¬
icon of application "DevonTHINK Pro"
end tell
tell application "DEVONthink Pro"
set allUnreadFeedPosts to search with unread
set cnt to 0
repeat with aPost in allUnreadFeedPosts
set postParent to parent 1 of aPost
if type of postParent is feed then
set parentName to name of postParent
set cnt to cnt + 1
end if
end repeat
if cnt > 0 then
tell application "GrowlHelperApp"
notify with name "New RSS posts notification" title ((cnt as text) & " new RSS feed post(s)!") description "Check them out in DEVONthink!" application name "New feed posts notifier"
end tell
end if
end tell