The DS and PSP are pretty break-even in NA and Europe right now (with approx ~5 million in each market, I think?), but the DS is ahead by about 2.5x in Japan.
(2004-2005's numbers were 4 million for the DS and ~2.25 for the PSP. 2006's [as of June 25th] have so far been 925k DS / 2.5 DS-lite and 900k PSP.
Current totals, then, are around 7.5 million DS and 3 million PSP. I think the software sales totals are even higher in the DS advantage, though. (Not sure about NA or EU. I REALLY wish they had Japan's quality tracking data.)
It's difinitively kicking ass in Japan, still maintaining a sales lead, and unlikely to slow down much (maybe it will only keep outselling by 3:1 or 2:1 as opposed to 5:1 in a few months
), but the PSP is certainly not a "no presence" item. The DS is simply a fad. ^_^ Nintendo's lead is not precisely shocking, but for the first time in basically FOREVER they actually has a challenge in the arena.
I think the longterm strength of both in all markets will in many ways have to do with what new and interesting things they bring to the portable arena--but moreover--just how well they can tie them in with their land-bound consoles. (Hopefully Ninty will do better than their abortive GBA/GC link, which mainly failed--IMHO--due to complexity of the connection. Not to mention NO developmental backing unless it seemed to "prove itself" overly with the first few titles that did anything at all. Wirelessness changes that rather mightily.)
In Japan's shortterm surrounding Wii's launch, however, it should be mightily affected by the Wii's novelty, PS3's looming budgetary woes, and basically
anything they can tie in with the DS.