A recent discussion on tT about Plaid's new Scintilli album suggested that it may be one of the best IDM albums of the year, partly due to a scant number of IDM releases this year. Perhaps fewer artists are releasing IDM albums these days, but I think compounding the issue is that many releases that may have been considered "IDM" 5 or 10 years ago are now considered Dubstep, Downtempo, House, Techno, Experimental, or "Mixed Styles". I know that the term IDM was derived from Warp's Artificial Intelligence compilation, but I've always thought of the genre as slighter broader than those pioneering tracks. When I first started listening to instrumental electronic music, I considered anything that wasn't ambient or intended/suitable for a club (such as house, techno, and drum n bass) to be IDM. Most IDM had both a melody and a beat, but it could have only one, and if it had neither, then it was Experimental. If it had a hip-hop beat, then it was Trip-hop or beat-oriented IDM, and if it was laid back and jazzy, then well, it was jazzy IDM. IDM could also include parts of other genres - so u-Ziq's Lunatic Harness, which certainly has breakbeats on it, is rightly considered IDM.
I hate to give examples, since examples are more easily argued. DFRNT (and other slow bass music) is classified as Dubstep on here, perhaps rightly so, but before there was dubstep, I probably would have considered this IDM. Detritus has been classified as Breakbeat, Mixed Styles, or Downtempo on here, but again, I think it could easily be considered IDM.
Perhaps my perspective is biased, since my first exposure to instrumental electronic music was IDM, and I've delved into other genres since then.
I know genre classification can be fairly arbitrary, but let me know what you think.