I'm using solar panels + a micro wind turbine to charge a decent sized LiPo battery using this circuit - http://www.adafruit.com/products/390. The problem is that the solar/wind stuff will produce a highly variable voltage (anywhere from 0 to 30V+). To feed the ada module, should I be looking at just a switching regulator, or are there other considerations given the high variability of input voltage and current?
The adafruit module looks good but it's only really meant for input voltages below 6V. To maintain efficiency you should use a low drop-out switching buck regulator capable of withstanding the 30Vs you might apply.
I'd recommend the AD8610 (mainly because I've used it on two designs): -
It's maximum input voltage is 42V so be aware of this. On one design I put a switch-off-when-the-volts-gets-over-35V circuit with a couple of MOSFETs just to protect it.
When you under feed it with voltage it still pretty much acts as a voltage follower be be aware of the under-voltage lock-out it needs to be tied to Vin to get the most out of it.
Yes one can use a rectifier-based DC converter to handle 0 - 30 volts input and rated current. The output voltage will be specified in tech specifications. Also check web for AC to DC or DC to DC step up/down converters as per your requirement.
You'll want a dedicated battery charging IC for this so you don't destroy your battery. There are a number available, and without knowing more about your specific setup (# of cells, charging current, etc) the best I can offer is this list of battery charging ICs. The LTC4000-1 looks like it will do what you want, but requires a number of supporting parts:
The LT3650-4.1 has a smaller voltage input range, but looks to be much simpler: