This is no longer a plan, but implemented as of Mercurial 0.9.3, see "hg help dates".

=== Supported Commands ===

hg log:

There is a -d/--date switch to show log entries from particular dates. Supported formats:

 * "{date}" - a single date
 * "<{date}" - on or before a given date
 * ">{date}" - on or after a given date
 * "{date} to {date}" - a date range, inclusive
 * "-{days}" - within a given number of days of today

We'll need to scan the entire changelog as there's no guarantee that there's any date ordering.

hg update/revert:

-d/--date results in scanning the log for the first matching changeset. This is usually what people want. 

=== Date Formats ===

Various date formats are supported. Here are some examples:

{{{
"Wed Dec 6 13:18:29 2006" (local timezone assumed)
"Dec 6 13:18 -0600" (year assumed, time offset provided)
"Dec 6 13:18 UTC" (UTC and GMT are aliases for +0000)
"Dec 6" (midnight)
"13:18" (today assumed)
"3:39" (3:39AM assumed)
"3:39pm" (15:39)
"2006-12-6 13:18:29" (ISO 8601 format)
"2006-12-6 13:18"
"2006-12-6"
"12-6"
"12/6"
"12/6/6" (Dec 6 2006)
}}}

Get more info on date formats with hg help:

{{{
$ hg help dates
}}}