From what I read about the issue, the component in Android that contains the entire media stack will be able to sync up with a newly revised version of the baseline media stack utilized by the basic android media player (and this newer version is slated to contain code for a multiband equalizer) at Android's revision 3.0 (whatever the codename for that is).
Until then, Samsung will likely be in the lead with its proprietary ports of its Multiband EQ stack, DNSe software stack, Presets stack, and other goodies ported from the YEPP series players to the Android Smartphone and PMP's... The ones listed above (Galaxy S, Galaxy Touch, and Wave-- confiirmed to have delicious hardware solutions to drive them: the Wolfson Micro WM8994)
Everything else... other than the early (THANKFULLY PARTIALLY CODED, and SEEMINGLY WELL DESIGNED ROCKbox.app/RaaA stuff) being pure heresay at the current moment.
This post is just to clarify what I've heard on the issue.
As for other endeavours on Android sporting some sort of EQ facility "in software":
1. Audio Player with EQ Platinum (features the Clear Sound engine, has a 10-band EQ with marked frequency steps, and works decently. I bought the app for my Cyanogen Modded G-1. It works
'adequately') WAV and MP3 supported here
2. MixZing is touted as having an EQ for MP3 file format
3. ASTRO Player has a multiband EQ with no labeling of what frequency register each bar represents, plus the bad distortion in the spectrum it introduces. I do not recall the formats it supports. YMMV.
I haven't had any luck finding any other EQ-supporting or capable apps for Android. If you know of any, may as well post to this thread since it may be helpful? Why not?? LOL.
Seems we have some interesting input happening as it is... and that's a good.
The only thing I really find missing from the Vibrant: Optical Out (heheHAHA, im ambitious) and IDE/CF/SSD support. To get one of those iRiver H140 compatable Compact Flash sized Zero Insertion Force IDE interface Solid State Drives with 128GB of room shoved under my battery shell. AGAIN being ToTaLLy Ambitious..... !! haha
hey I realize no product has been perfectish since the iRiver H140, but i'm just saying. add those two features to a Galaxy S class device witha honkin batt, and I'd be happy. I dunno bout you folks. Yes, that was sort of an invitation for discussion... :-D