Regarding mac clients, metalmudder is the best one I've found so far, although mudwalker has some nice features. Not totally satisfied with either, but I thought I'd chime in that they seem to be the only ones that work pretty well on OS 10.4 and up.
Can't speak for blackberries or iphones tho.
If anyone, however, knows of a better mac client for 10.5, I'd be interested to hear it. Thanks!
Written by my hand on the 28th of Midwinter, in the year 1251.