My wife recently went to install a game on her phone (Sims Freeplay) from Google Play. She tells me the phone had enough memory for the install (~15MB free for a 13MB app), which is why she tried.
(As an aside, I'm assuming it downloads the package, then installs from that, so you need at least twice the final space to unpack the thing correctly.)
It downloaded successfully, but when the phone tried to install the app the phone unexpectedly self-rebooted.
After booting, the game wasn't installed and the phone is reporting low memory, with <1MB of phone memory free. She's using an app to check this usage (called DiskUsage), which is reporting "System Data" as using 28MB - she's sure it was much smaller when she checked the space before attempting the installation.
Assuming she's right, I'm thinking maybe the downloaded package is still sitting around somewhere consuming space. Is this possible (given it crashed mid-install)? If so how can we get rid of it?