Since Peter, myself, and many others actually do have the latest (.3) versions of iWork '09 applications working just fine on Yosemite, perhaps the issue is with your installation procedure.
Before October 2013, the last versions (n.3) of iWork '09 applications were downloadable from the OS X App Store. Because the Frameworks (libraries) that they require, are self-contained within each application, these can be placed on a USB stick, and deposited into a /Applications/iWork '09 directory on Yosemite. The iWork '09 DVD applications are n.0 versions, and do not have self-contained Frameworks, as the DVD installs these in the System area of the destination Mac. The only way these applications will work correctly on Yosemite, is by a fresh iWork '09 DVD install, followed by the Apple iWork 9.3 updater to yield last (n.3) application revisions.
Which ever approach in paragraph 2 above is applicable to you; it is wise to follow this with Disk Utility and verify/repair permissions for the current (Yosemite) operating system. Wrong permissions on an iWork application can be very annoying.
With iWork '09 and current OS X App Store iWork applications (e.g. Pages v5.5.2) jointly installed, one must be doubly careful because the current iWork applications use a new document architecture that is not compatible with iWork '09 applications. Double-click on a Pages '09 document, and Pages v5.5.2 will open it by default. That is not the end of the bad news either. Pages v5.5.2 lacks 100+ features that were found in Pages '09. Workgroups sharing mixed documents will incur additional work because Pages v5.5.2 will remove or undo content it does not support from earlier Pages '09 documents. Then it auto-saves into the new document architecture. Exporting Pages v5.5.2 content to Pages '09 documents will not calm the original document author.
The amount of lost workgroup productivity in mixed iWork document environments is appalling. My workgroup is comprised of about 200 Macs that must have document interchange with other mixed Mac and PC organizations. Apple's Pages application is banned from all Macs. It is Office for Mac 2011 with latest patches, so everyone for the most part, can work in one, native (.docx, .xlsx, .pptx) format.