Although it's not in Cubase at the time of writing, at the request of well-known and technologically-astute German film composer, Hans Zimmer, Steinberg have re-implemented a version of the Cubase VST-style Process command (which used to reside in the Do menu of the Mastertrack editor) in the latest version of Nuendo. While Process isn't quite as visually interesting as the Timewarp tool, it provides a quick and efficient way of dealing with multiple tempo events in one command.
Taking film as an example, say you've written a piece of music that lasts a minute and is structurally perfect, but now the picture gets re-cut slightly so that the piece needs to last 55 seconds instead. Your music contains Tempo Events, and rather than rewriting or editing the music, you want to simply compress it, while keeping the shape of the existing Tempo Events, to make the music fit the new length of picture. The way to do this is to scale the tempo of the Project and all the Tempo Events it contains proportionally, but doing this manually, one Tempo Event at a time, would be fiddly, to say the least. So instead, there's the new (or old, depending on how you look at it) Process feature.
Using Process is fairly straightforward. Open the Tempo Track Editor (Project / Tempo Track, Apple/Control-T, or Apple/Control-click the Tempo button on the Transport Panel), select the Tempo Event you want to adjust and choose Edit / Process Tempo. Note that you won't be able to open this window if no Tempo Events are selected. The upper four boxes show the start and end times of your selection in musical (PPQ) and linear time, and it's possible to adjust the selection range from these fields. The end point should be the musical point that you want to match to a new time location.
In the lower part of the window, Current Length shows the length of the selection in the selected Format (this will normally be Timecode), and you type in the new time location you want to hit in the New End Time field. This will automatically work out a new length and a suitable Scalar value (to scale the Tempo Events by). When you hit Process, the selected Tempo Events will be adjusted so that the end selection point specified in the upper part of the window matches the New End Time in the lower part.