Overall:
-build: Go 1.4 required to build (https://golang.org/cl/2470, https://golang.org/cl/2993)
+Language:
+permit omission of key type in map composite literals where key is a composite literal (https://golang.org/cl/2591)
+
+Build:
+Go 1.4 required to build (https://golang.org/cl/2470, https://golang.org/cl/2993)
New Ports:
Darwin/ARM, a.k.a iOS. (https://golang.org/cl/2118, 2119, 3273, 2121, 2122, ..., 2127)
flag: new nicer format for PrintDefaults (https://go-review.googlesource.com/7330)
go/ast: add Implicit field to ast.EmptyStmt; changed meaning of ast.EmptyStmt.Semicolon position (https://golang.org/cl/5720)
log: add SetOutput functions (https://golang.org/cl/2686, https://golang.org/cl/3023)
+math/big: add arbitrary precision Floats (many cl's)
net/http: support for setting trailers from a server Handler (https://golang.org/cl/2157)
net/http/cgi: fix REMOTE_ADDR, REMOTE_HOST, add REMOTE_PORT (https://golang.org/cl/4933)
net/smtp: add TLSConnectionState accessor (https://golang.org/cl/2151)