Strictly speaking, the StrongARM isn't an ARM - it was 100% designed by DEC, and as such, it has none of the heritage of the ARM1 in it. ARM7 is essentially ARM3 with go faster stripes, and ARM3 is essentially ARM1 with go faster stripes, where the ARM8 never worked, and the ARM9 and ARM10 are very different indeed. Yes, this does actually mean ARM have finally designed a CPU that worked! All their others were either tweaks to ones Acorn designed, bought off somebody else (see the NEC synthesisable ARM that was found in 3DO machines), or just has their name thrown on it for marketing purposes (StrongARM, XScale).
It's a good milestone though - I hope they go for another 20.