I use it on an iPad - not the same as an iPhone I know - but there's
an app for tiddlywikis (TWMobile is the iPad version and TWEdit the
iPhone one... AndTidWiki is listed at
tiddlywiki.com for the android)
that lets you save it to the iPhone/iPad. For me, I save it both
locally and online to the tiddlyspot account I got (free if you
haven't made one). Thus... I have a local copy on the go I reference,
and a synced online one for most of my desktop work. After desktop
work, I download it again, use iTunes, and transfer it to the TWMobile
app (very quick to do this as it doesn't require a whole sync of the
phone).
The trick for the iphone is to get an interface that is usable on the
small screen. I put the sidebar items I wanted in the sitesubtitle
tiddler and cut the sidemenu out completely. It took me a bit to get
used to the two finger scrolling to scroll the contents of a tiddler
that was longer than the screen, and some tinkering with the
stylesheet tiddler to increase the font sizes to a more readable
one.
Thus, the possibilities are there... try typing on the notepad app on
a demo phone at the store... If you are ok with what you type and
read, you likely will be ok with a wiki on a phone, but if you are
not... then you likely won't like it...
Hope this helps...
Rich