Without giving any reason, Google has pulled off the PSX4Droid PlayStation emulator from its Android Store.
When the program's author, ZodTTD, asked for a reason, Google responded with a generic "We remove apps from Android Market that violate our policies."
The sudden removal of the emulator after it has been available for eight months seems to suggest that it has something to do with the imminent launch of Sony's Xperia Play, a.k.a. the PlayStation Phone.
It is worth noting that other emulators such as SNesoid (SNES), GameBoid (Game Boy) and, interestingly, FPSe (PlayStation) were not affected.
PSX4Droid is available through third party Android app-markets.