I was kind of bored so I did a little research and started making a list of major rides announcement dates. (Yes I may have gotten a bit carried away)
*indicates a Cedar Fair attraction
BOLD indicates a B&M Hyper. *cough*
Voyage announced 7/13/05
Kentucky Rumbler semi-announced 7/28/05
Storm Runner announced 8/5/03
Apollo's Chariot announced 8/5/98
*Diamondback announced 8/6/08 (Earliest track sighting 7/23/08)Griffon announced 8/23/06
*Behemoth announced 8/27/07 (Earliest track sighting 8/23/07)
Goliath (SFOG) announced 9/1/05*Prowler announced 9/1/08
*Maverick announced 9/7/06
*Patriot announced 9/7/05
*Hydra announced 9/14/04
*Renegade announced 9/21/06
Goliath (SFFT) announced 9/27/07
Evel Knievel announced 9/27/07
Fahrenheit announced 9/27/07
El Toro announced 9/28/05
Kingda Ka announced 9/29/04
*Thunderhawk (Michigan's Adventure) announced 10/2/07
Raging Bull announced 10/21/98Terminator announced 10/22/08
*Dominator announced 10/23/07
Goliath (La Ronde) announced 10/25/05Sheikra announced 10/27/04
Titan announced 11/14/00
Tatsu announced 11/17/05
*Top Thrill Dragster announced 1/9/03
Nitro announced 2/1/01*Firehawk announced 2/5/07
I also found the dates for Carowinds announcements:
9/10/08 Carolina Cobra
11/5/07 Bondi Beach (Yo-Yo I can't find)
1/27/07 Southern Star
9/22/05 Boomerang Bay
1/31/05 Phantom Flyers/Flying Dutchman/Nick Central Phase II
8/21/03 "Flying Coaster" announced, Borg name announced 1/15/04
8/17/02 Rugrats Runaway Reptar/Nick Central
10/22/01 Ricochet/Carolina Boardwalk
12/13/00 Scooby Doo, Pipeline Peak, 7th Portal
1/13/00 Super Saturator
7/12/98 Top Gun
The only thing I seem to have deduced is that it is going to be a long, long summer.