Anything could have happened, of course. Sounds like it wasn't even a beta. Odds are the app is still there, just invisible to your phone's UI. Possibly a damaged file header.
Have you got any links to Sparkle or location labs?
What I would do is:
1) get in touch with the dev. As a beta user you have a way to contact them, submit bug reports etc. don't you?
2) see if I could find that app somehow anyway.
You did reboot the phone since, didn't you? Still no Sparkle app?
Gave it a good look around on your phone and your SD card with a file manager? Like Android's built-in one in the Settings. Or File Expert, ES File Explorer, WiFi File Explorer, etc.
Or, if you really want to dig, do a data dump of everything on your phone to an external medium/HD, then go take it apart on a Linux machine. At least you'll get decent search capabilities to get around the thousands of files, notably absent from its mobile cousins.