No.
Or at least, not entirely.
The pause is dependant on the amount of stuff you have on the hold and the number of OXPs you've got. Most OXPs that add/remove stuff to the system, do so just as you launch from the station. Until they're rewritten to take advantage of the fixed .startUp event instead, the delay stays exactly where it is now.
The timer mentioned by Eric, and missionScreenOpportunity mentioned by Svengali are 2 methods already used in a few OXPs. OXPs that use those methods are already avoiding shipWillLaunchFromStation, so the net speed improvement for those OXPs will be 0.
One other thing: if you've got a lot of stuff on the hold, like Switeck's 4K-plus tons, Oolite will need to pack the cargo in individual cargo containers. This behaviour is linked to a few critical in-flight features, features which we're not going to mess with during a feature freeze.
On 'vanilla' Oolite, carring 35 tons on my cobra 3, there's no discernible delay, at least on a 3 year old core 2 duo laptop!