He has to still see fastballs more than any other pitch. He probably sees more sliders than almost anyone, but it's not going to outnumber fastballs.
I think most of this data comes from Stats Inc., but I don't know anyone who has access to that stuff.
I was curious about this as well, so I looked back at MLB's Gameday for the last 11 games (I don't recommend doing this, it's not that fun). 11 games is a ridiculously small sample size, so I don't know that this really shows anything. Why 11 games? I'd originally planned on just doing 10, but one of the game's (7/26/08) data was pretty bad (5 of the 7 pitches Hunter saw that day were undefined). Another caveat is ... well, who really knows how MLB gets this information?
Here's what I found in this totally useless exercise:
156 total pitches seen
68 Fastballs (43.6%) - 9 hits
34 Sliders (21.8%) - 3 hits
22 Changeups (14.1%) - 0 hits
18 Curveballs (11.5%) - 1 hit
3 Splitters (1.9%) - 1 hit
1 Sinker (0.6%) - 0 hits
also
6 undefined pitches and 4 intentional balls
Again, this is a ridiculously small sample size and proves ... well, absolutely nothing (I'm assuming; I don't have any idea what a good sample size would be). It may also be worth noting that Hunter's on a nice little hitting streak right now (his average has risen 13 points in the last 10 games) so maybe he was seeing a lot less fastballs earlier.
As for people thinking that Hunter never gets fastballs, it looks fairly close to me (and yes, I understand that no one said "never"; I'm not the first person to use hyperbole on this board). We just see him swinging horribly on the offspeed stuff, so that's what sticks out in our memory the most. Watching the game is absolutely the most important thing we can do to understand what's going on, but our memories aren't perfect.