I was a paying Google/Picasa Web Album customer  when Google introduced its integrated Gmail + Web Album storage model. That meant I started off with 10GB combined, based on the $20 or so I was paying for my photo store. I've used 4.5 GB, or what was almost 50% a day or two ago.
Today I'm back at 34%: "4.5 GB (34%) of 13 GB". Google has increased the storage pool by 33% for the same price. I've read that this will be their model going forward -- keep the price the same, but increase the store.
I like that model.
Curiously, back when I just used Gmail, I'd typically run at 30-35% of capacity. I was using storage up at the same rate that Google was adding it. Now, in the combined model, I'm back in the same range.
Things will change if Google ever introduces an S3 type online data store, or an online backup service. Then I'll need to buy a lot more storage. Given their current problems  I don't expect to see that before the middle of 2008.
 This was back when their Web Album iPhoto plug-in actually worked. Apple's iLife 2008 broke it two months ago, and Google has been unable or unwilling to fix it -- or even to let users know it doesn't work any more. This fits with my recent Google Apps experience. I don't need the recent 'Google to Facebook exodus' meme to tell me Google is struggling.