Sent my 23 coupons - 25 sector itinerary to Air Canada RTW desk for pricing. Got a reply with this sentence in bold:

Please note effective May01/08 the Star Alliance Web-site will no longer be processing itineraries longer than 16 segments which would include surface segments. Should your itinerary work out to be more than 16 segments please have your request submitted prior to the 30th of April. Allow enough time for all airline confirmations to come thru (48hours) and your reservation must be paid and ticketed prior to end of business day on the 30th of April.