Short version - it's a help but it hasn't fixed the problem, just made it less bad than it was previously. Long version see below.
Some rain has fallen across the whole state but there's a huge variation in the amounts and where it fell.
The heaviest falls were on the East Coast as such, which runs off via local creeks and rivers (not via any power station) and also into the Mersey-Forth and South Esk catchments, both of which are used for power production.
So the practical effect of that rain has been to put Trevallyn power station (South-Esk catchment) and the lower sections of the Mersey-Forth scheme into base load production using the incoming water. This production, along with the present high level of generation from wind, has enabled other parts of the hydro system to be either totally shut down or at least have their output reduced.
That then helps conserve water elsewhere in the system and is also facilitating some maintenance works at those power stations which draw upon the major water storages and which have been operaing at very high levels in recent times due to the overall situation.
So in short, some rain has fallen and it has lead to high production levels in two schemes but it's nowhere enough to actually refill the major storages. Eg Great Lake (a major long term storage) was 17.55m (measured vertically) below full before the rain and is 17.40m below full now. Arthurs lake has gone from 3.26m up to 3.14m below full. Both of these have received decent rain, with Great Lake also benefiting from the reduced need for power production from that source.
Lake Gordon is 41.57m below full (that's not a typo, it's 41.57m down from the top measured as a straight vertical drop) and hasn't really increasd at all. But with production coming from elsewhere, the decline in the level of Lake Gordon has at least been halted for the moment - in other words it would be even lower now if not for the rain elsewhere.
A key part of the issue here is that the soil was so dry before the rain, much of the state needing around 150mm just to saturate the ground. Only after that does the big run-off occur. So a lot of the rain has simply soaked into the ground, the Mersey-Forth and South Esk catchments being the exception due to the very high rainfalls over a short period.
On other matters:
Gas - there's an open cycle gas turbine overseas being repaired at the moment and it has been decided to air-freight it back after repairs rather than to ship it in view of the overall situation. The bill for the air freight is about $70,000 more than sea freight would have cost but means it will be back in service early in April. This unit is fairly new, 2009, so should be reliable once the problem is fixed.
At present all available gas-fired plant, that is the combined cycle unit and the 3 small open cycle units presently in service, are running at full load 24 hours per day. Open cycle gas turbines aren't ideally suited to that role, and the 3 small ones are fairly old too, but they're working reasonbly well thus far (a few minor hiccups at first but they're going well now).
Diesel - 24 MW of portable diesel generators (1 MW each) have now been sourced from interstate and are on their way to Tas, to be ready for service (base load if necessary) in March. The intent is to source another 34 MW on top of that. These will be connected to the grid and operated collevtively as a power station. They are containerised units, so literally the same size as a shipping container.
The chance that the diesels will actually be run is low, but it is not zero hence obtaining them. The fuel cost is going to be pretty serious if they do need to be run. The 58 generators, plus another couple that we already have as standby mobile generators (bringing the total to 60 MW), will between them use about 400,000 litres of diesel each day.
Bringing in the diesels and speeding up the return of the gas turbine is basically a plan in case Basslink isn't fixed in March as planned and/or if severe drought continues. Most likely they won't be necessary, but there's a lead time to obtain them, ship them across, get everything set up on site and so on hence doing it now.
Basslink itself is being worked on by the onwers but at this stage nobody seems willing to firmly commit to a date because they still haven't lifted the cable, which is under a metre of sand, to inspect it. That being so, nobody's sure what they're going to find until it is raised to the surface for proper inspection.
Overall there's still very little chance of the lights going out but it would be fair to say that things haven't been going well lately.