"Compositions created with a previous version of After Effects that use the Vector Paint effect will still render in After Effects CS5, but you will not be able to modify the Vector Paint effect properties in these compositions in After Effects CS5.
In other words, it's the Vector Paint UI (user interface) that is missing from After Effects CS5, not the underlying effect for rendering."
The lack of Vector Paint and the ability to paint directly in the comp was also bemoaned on the AE-list recently, as well as on the release of CS5. A partial workaround for wiggle was shared by Trish Meyer on March 8, 2010, "You can copy and paste paint paths to Shape Paths (created by the Pen tool) - just make a dummy path by clicking with the Pen to create it, then paste to it."
Note: since CS4 was shipped with CS5, you can use it for missing features and plug-ins.