Yes, but in the sake of compatibility, you would use a .zip (Yes, a .rar may be slightly smaller, but what about the Mac users - yes there isn't too many of them - but it's still an extra fan, such as Avenger here).
such is true, this is why (on most, but not the latest) I've kept both Rar and Zip versions available. I'll upload one for 2.29
If you REALLY were so eager about compression and not about compatibility, you'd go with a .uha.
Theres a third point, that really has sold Rar's for me... thats the program itself. The Rar file browser is simply fantastic. It has an increadible range of extension support, and it maintains the internal directory structure of the file, unlike winzip and many other popular compresion tools. And, it maintains an acceptable compatability level and is reasonably well propogated across the user base.
Its not as simple as Compresion vs Compatability. Its more like
Compresion vs Compatability vs Ease of Use vs Propogation. Winrar has the best blen of all 4, while the zip has only the highest compatability.