worried about an app

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.

 

Doing what exactly?

Good question for the dev...

Yes, under your Gmail ID and password.

 

You dont need to reformat I think, try checking installed apps from the settings menu.

 

From a quick look at their website, I'd say it's only of interest to developers, not end users.

 

If he can't find it, he can't uninstall it.

Sounds as if this 'Sparkle' was a sideloader. If so, will it show up in the installed apps list?

 

I think it should. I too have a couple of sideloads that show up there.