Yoshi was extremely useful in Sunshine, he was just sorely under-utelized. Improved spin jump, flutter jumping, creating platforms out of enemies and cleaning up electric slime to progress or uncover hidden areas.
Seriously, all I ever wanted was more galaxies because when SMG was done I felt empty inside. Thank you Nintendo, between this and a new Metroid and Golden Sun DS you have almost redeemed your year of total crap!
Happy to be proven wrong. I never expected them to announce a sequel so soon, although I'm a little disappointed it's a 2010 title, polish was a big part of what made Galaxy great, so I'm not about to complain if they think they need the time.