Update: For you Debian and Ubuntu repository users, the new avr-libc version with this patch are going into your repositories. I just received this:
Comment #7 on issue 604 by showard...@gmail.com: wiring.h round macro causes error with avr-libc-1.7.1 fix
http://code.google.com/p/arduino/issues/detail?id=604Linux distributions just upgraded their gcc-avr to 1.7.1 too. Debian/Ubuntu/Mint's version of arduino has this patch:
http://patch-tracker.debian.org/patch/series/view/arduino/0022+dfsg-4/libc_1.7.1.patchBug-Debian:
http://bugs.debian.org/633659--- arduino-0022+dfsg.orig/hardware/arduino/cores/arduino/wiring.h
+++ arduino-0022+dfsg/hardware/arduino/cores/arduino/wiring.h
@@ -76,7 +76,7 @@ extern "C"{
#define max(a,b) ((a)>(b)?(a):(b))
#define abs(x) ((x)>0?(x):-(x))
#define constrain(amt,low,high) ((amt)<(low)?(low)

(amt)>(high)?(high):(amt)))
-#define round(x) ((x)>=0?(long)((x)+0.5):(long)((x)-0.5))
+//#define round(x) ((x)>=0?(long)((x)+0.5):(long)((x)-0.5))
#define radians(deg) ((deg)*DEG_TO_RAD)
#define degrees(rad) ((rad)*RAD_TO_DEG)
#define sq(x) ((x)*(x))