Very, very helpful.
Where as I find a not so obvious issue with recompiling. At least on Windows XP and 7, likely others Windows. (and likely not on Linux). The "is_already_compiled" enhancement (from Paul Stoffregen) does not appear to work when ERW is installed into the recommended default directories. Through experimenting I have determined that it is due the white spaces in the pathname. Such as "C:\Program Files (x86)\Arduino\Arduino ERW 1.0.4" for Win7 and "C:\Program Files\Arduino\Arduino ERW 1.0.4" for WinXP. It is best seen with the IDE's preferences enabling verbose output for compilation.
Simply moving and renaming to "C:\Projects\Arduino\Arduino_ERW_1.0.4" then allows recompile's to take advantage of the "is_already_compiled" feature, for subsequent compiles. Speeding them up. Note the underscores (replacing the white space and yet the periods are still there.
Simply running the arduino.exe from a short cut, using 8.3 brief names (such as "C:\PROGRA2\Arduino\ARDUIN1.4" does not work. Neither does it work executing "C:\PROGRA2\Arduino\ARDUIN1.4\arduino.exe" from the RUN prompt. Where it does work correctly from a CMD prompt. Note the issue likely is not with the path of the temp file, but that of arduino.exe.
Note being an expert, but I believe the symptoms indicate the issue is related as to how java is treating the paths with its modified tests.
As a result in that the ERW installs using such a pathname, this subtle but very helpful prior feature is disabled.