For my purposes, the 35mm focal length equivalents for the 4/3 system are a bit lower than advertised, so that for example the 14-54mm Olympus E-system standard lens is better compared to 25-96mm in 35mm format; and this gives it an even clearer advantage over any one lens yet announced for the various "cropped 35mm" DSLR's. (Nikon probably has something coming though.)
The reason comes from the ambiguities of comparing with different image shapes, and the fact that Olympus compares on the basis of frame widths (18mm vs 36mm so a factor of 2), which makes sense if you are going to print at the 35mm shape as with 4x6" prints.
However my wide angle shots are usually somewhat squarer compositions, and if one prints at any of the squarer shapes like 8x10, 11x14, 16x20, 8½ x11 or 6x8 you are cropping at the sides and using the full height, and so should compare on the basis of frame heights: 13.5mm vs 24mm, a ratio of 16/9 or about 1.78.
To put it another way, if you use any camera of squarer aspect ratio than 35mm and mostly compose and print in terms of its native shape, you should compare to 35mm by frame height, not width. Most compact digicams are in the same situation: those 35-105's are 31-93 for me.
P. S. The shape of A4 and such falls in the middle, and the advertised equivalents are only negligibly high for them.