Would something like this be useful?
--- develop.html.~1.114.~ 2011-03-26 10:44:52.000000000 +0100
+++ develop.html 2011-03-26 10:58:49.311173994 +0100
@@ -434,13 +434,13 @@
| GCC 4.5.1 release (2010-07-31)
GCC 4.6 Stage 3 (starts 2010-11-03) \
| v
- | GCC 4.5.2 release (2010-12-16)
+ | r167945 GCC 4.5.2 release (2010-12-16)
|
+-- GCC 4.6 branch created ------+
- | \
+ | r170934 \
v v
GCC 4.7 Stage 1 (starts 2011-03-14) GCC 4.6.0 release (2011-03-25)
- |
+ | r171512
|
v
The idea is to include the copy-source revision on the trunk or the
respective branch, so that you can use the timeline to check whether a
particular change came before or after a release. Of course, this is
just an approximation, but it think it might still be useful.