Incumbents are generally safe unless someone else comes along that really wows people, or if voters are too angry with the current administration. There may be some ongoing anger due to the ongoing infrastructure debacles (Metro LRT, Walterdale Bridge, infill), but so far there's nobody credible enough to knock off the majority of the incumbents.
http://daveberta.ca/edmonton-election/
Mayor - is Iveson's to lose
Ward 4 might heat up because there's no indication if Gibbons will run again.
Ward 6 - McKeen is popular enough that he won't have to run against 24 other people.
Ward 7 - I'll take Caterina over that nutjob Mimi Williams.
Ward 9 - will be the only one that will matter because someone new will replace the retiring Bryan Anderson.