In the coming update (in a few hours time) there will be some drastic changes to the way saves are handled online. traditionally, whenever you save something in The Powder Toy, it is published online and added to the search for anyone to view, this is about to change. There will be 2 types of saving: public and private; public saves are viewable to anyone, while private saves are viewable only to you (but this is by no means secure, so don't put passwords in your private saves) There will be no restrictions on public or private saving, but it is important to respect other authors when saving publicly, this is something you do not need to worry about when saving privately. By default, a save will be private (unless you're re-saving your own published work) it is as simple as a check-box away from being public.
While public saves are available in the main search and private are not, to view your own private work, simply click on "My own" on the search screen. You can also send your private saves to friends by linking them to the save in the browse section, which will be also feature a search in the near future.
It should also be noted that the decision has been made to make all saves currently on the server as private, they will keep ratings and tags, you may publish your saves by opening them from the "My own" section and re-saving them with the "Publish" box checked.
We will also stop deleting saves (except during certain circumstances) instead, we will just "unpublish" them to make them private and non-visible to others.
Simon I cannot confirm that behaviour at my end, which version are you using? Edit: Wow, I panicked and rolled back the update... Don't do that again :P