I know you'll will be able to. If not, someone else will.
R-pi will likely become a Zeebo of the DYI/Hacker community - http://en.wikipedia.org/wiki/Zeebo
. Zeebo is a console for the BRIC countries with downloads and connectivity via mobile phone networks. It's an ARM11 at 528 Mhz running BREW. (The R-pi Model B's just need a Bluetooth and Wi-Fi dongle to achieve the same thing.)
Since DYI's like to case mod, it will be stuffed into handhelds, hung on the back of HDTVs with HDMI, etc.
First, you might want to check out some of Ben Heck's fine work for the hardware side of it - http://benheck.com/all-game-projects
. Email Ben about this and he might even take on the challenge.
If this is your first rodeo (attempt), it might be bigger than a Sega GameGear. In fact, if you use one of those portable Digital TVs, at 7" diagonal you might need handlebars for it. ;-D
As for the emulator side of it, many of emulators run just fine on ARM. I have a Linux powered GP2X Wiz (ARM, 533Mhz, 64 megs) and their community forums have a linux ARM "distro", plenty of emulator source code and forum discussions on compiling you could leverage on ports like Doom & Quake, console & handheld emulators, etc. My GP2X Wiz can even run the PSX emulator on it in a some what usable fashion with just 64 Megs RAM. (And yes. I own a working PSone + its display and ~40+ games for it.)
- has lots of great "External Links"
For inspiration and guidance on a custom Emu Distro, you may wish to look at Puppy Arcade put together by Scott Jarvis - http://scottjarvis.com/page105.htm
. I was running the 109 Meg ISO in VirtualBox OSE with 196 megs RAM without any issue.
If the game Emu's packages don't exist on day one, I guarantee they will arrive in droves shortly (zero-day most likely) after the R-pi's start arriving in folks hands.
Cheers, Mark S.