There is an IDE available at the Software Downloads https://communities.intel.com/docs/DOC-23242 that works for both the Edison and the Galileo board. As for integrating that Edison/Galileo IDE to the Arduino IDE there are currently no plans to modularize so that all boards can work in a single IDE.
I can follow you and to some degree, I agree, that it would be nice to have one IDE and then a bunch of plugins for each target platform. Today, there are a lot of forks of the Wiring IDE, where the biggest fork is the Arduino flavor, and they actually did a lot of work a year or two ago to make it easier to add in different platforms (they needed both AVR and ARM when they launched the Arduino DUE).
The current editor in these IDE's isn't really that good, there are a lot of functions missing that would be really nice to have, but for beginners and other non-native-coders (a big target audience for this IDE), the simplicity is a good thing.
The project embedXcode is looking at it a bit differently, where each of these IDE installations are seen as "plugins" with all the cross-compiler and library stuff, and Xcode on the Mac is the development environment with all the nifty editor features pro's are used to.
So if you are on a Mac, embedXcode might be an option for you!
PS: I'm not related to embedXcode, have just tried it and like the effort to bring in a better editor.
PPS: I'm not sure the Edison is supported yet, but likely will be in the future.
If there is no intention to merge in the Intel platform support into the regular Arduino IDE (the one with AVR, ARM, etc. support) wouldn't it be an idea to officially use the color theme previously released here on the forum (galileo_theme.zip), so that the IDE windows are easily recognized when you have multiple IDE's running at the same time.
I can add it in myself, but doing it every time there is an update is a bit tedious.
Just an idea!
I totally agree with the IDE isn't that great because its not. I think their first mistake was using Java. While it might be ok for Windows and Linux, it isn't for OS X. I have held off for many years installing JRE on my Macs and even the idea of loading it makes me sick.
I think the IDE needs to be rewritten from the ground up to support any and all Adruino hardware. Even if it is based on Eclipse is used as a base and the installer leaves you with a usable IDE instead of a 6 page howto on getting Arduino to work with the "factory" Eclipse. Now getting Eclipse working with Arduino is so frustrating I believe most people just give up and go back to the Arduino because it just works. Isn't that why the Arduino IDE is so popular, because it just works, however inadequate it maybe?
I move from Windows to Linux to Mac all day and it would be nice to have a simple IDE that works the same on all with the power to increase the functionality without exponentially increasing complexity. Is that too much to ask for?
Hmm... personally I'm not a big fan of Eclipse either, that's also Java by the way.
The direction the Arduino team is heading is with a web based IDE, running on the device (that's what they use on the Arduino TRE, and if I'm not mistaking, they have talked about doing something similar with the Arduino YUN). That is of course not gonna happen on the smaller microprocessors in the same way.
As it is now, I don't think there is a good cross platform IDE, especially if you don't like Java as the base for it, that could be used as a base for a plugin structure.
The future for broad processor support IDE's is probably in the cloud like mbed.org or something like that, but it's tricky if you want to put in some debugging features.
Alternative is just command line tools, your favorite editor and make scripts to glue it all together ;-)