IssueTracker

Another alternative would be to have specific time windows for monitors.

For instance:  Monitor 1 active from 7am - 8PM  (notifies email1@domain.com)
Monitor 2 active from 8pm - 7am (notifies email2@domain.com)

The ability to assign time ranges to policies would be a huge advantage.  Certain services that are being monitored may only be subject to an alert policy between certain times/days of the week (for example, a web service may need to be available Monday - Friday between 09:00 and 20:00, but outside of those days/hours, it may be subject to routine maintenance for which an alert does not need to be generated as it is expected to be unavailable).

I can see that this issue has been assigned, but it's been a while and this would be a great feature to add in whilst the 'condition editor' is in beta.

Our company would love to have this feature included as well.

+1 on this.
The snooze feature would enable the ability to create alert policies for each condition/timeframe, and then snooze the alerts when not needed. BUT having to create a snooze for every day manually through the console is not scalable.
Alternatively, just being able to set a time window in which metrics based alerts fire(as part of the alerting logic) would also serve this goal.