Last Friday I walked from Little Wobby to Rocky Ponds and back, which is described on the wildwalks website here. You need a permission letter from the Broken Bay Sport and Recreation Centre to walk through their land, but it's easy enough to get (ring 4349 0600 and they'll send you an email).
The only way to get to Little Wobby is by ferry; I left from Brookyln at 7:40 am, and got back around 5:30 pm. The timetable here seems to be up to date. I rang to check the ferry times, and I loved the message I got the first time: "None of the ferry operators know how to use the answering machine, so please don't leave a message -- just try again a bit later."
Here's a map of the walk; the green triangle is Wobby Wharf, and the top "i" square is Rocky Ponds. For an interactive map see here (there are some other Sydney bush tracks on this page). Note that the south section of the main trail is not included.
Little Wobby is a row of less than a hundred houses along the shoreline facing Dangar Island. It isn't too far from the ocean, and there are lots of oysters clinging to the rocks and a bit of a sea scent in the air. The walk south from the wharf goes around and under several houses until you reach a large grassy clearing and a (kind of) road. On the return journey I took a short cut that ended up back at this clearing.
I followed the road to a point just past a beach on the right, then went left (north) up a fairly steep track through a couple of caves. The track became pretty unclear with some false side tracks, and I lost it completely at one point. The path I took looks pretty similar to one on the wildwalks page, though.
After a while I hit the main track and headed north again. It had been raining earlier and the track was quite overgrown, so I got pretty thoroughly soaked from brushing past wet plants. There are some clear, easy sections along the track, but also a few places where you have to bend very low to get under branches. The views over water are very good, though.
The cascades at Rocky Ponds are very beautiful and quite extensive. They are also very shallow, so you can walk around a find a good spot to take photos.
After exploring for a bit, I continued southwest along a track to the right of the creek, and reached the top of a high waterfall. The track continued a bit further to the "Icicles", a rocky outcrop. I didn't follow the track any further down, though I think it might reach the beach at Tank Cove.
I doubled back and decided to walk back along the creek itself instead of the path (from the top of the waterfall), which was really fun. It's easy to rock-hop most of the way, and I found some short tracks on the other side of the creek which helped get past some tricky bits. There are lots of lovely pools and small waterfalls on the way.
On the way back, I tried a different track to the left of some powerlines down to the clearing. It got quite steep and potentially slippery with loose dirt in places. Going up this path could be hard, since there were a few places where I had to jump down to the next rock. It's hard to see the track from the edge of the clearing; there is a post nearby with a metal imprint that says "ten" on top of it.
The route I took was 12.5 km altogether, but it was slow going due to the overgrown track and I had a pretty relaxed pace anyway, so it took about eight hours (which still left an hour to spare at the end).
Rocky Ponds is a beautiful area; recommended if you don't mind being hit in the face by stray branches and bending down under fallen trees on the way!