I'm suddenly running into the same issue with B69 on 10.7.4, for single command modifier only activation. Not sure what's up yet.

On Tuesday, July 24, 2012 9:03:41 AM UTC-7, Brandon Blattner wrote:

And, as odd as it may sound, today it's suddenly working, seemingly out of nowhere!  I don't know what to say aside from to apologize for complaining about something that fixed itself!  Everything's great now!

Thanks anyway!

Regards,

Brandon

On Monday, July 23, 2012 9:06:25 PM UTC-4, Jon Stovell wrote:

All forms of modifier-only activation are working for me using QS β69 on OS X 10.7.4. If you cannot get it to work, you may have something interfering, like Rob said. 

If you cannot figure out's wrong, an alternative might be to install KeyRemap4MacBook (which, despite its name, works on any type of Mac) and set a custom configuration in there to send your normal QS activation keystroke when you press Command twice.

On Monday, July 23, 2012 5:37:23 PM UTC-4, Brandon Blattner wrote:

I have always used Double-Command to invoke Quicksilver as well and now can no longer use it - please let me know if you found a solution to this! Thanks!

On Tuesday, June 19, 2012 5:47:08 PM UTC-4, Boots2x wrote:

I've been happily using Double-Command to invoke Quicksilver for quite a while now - it broke some years ago but was fixed. Seems like the latest release broke that combination again. The default [Control-Space] works correctly. If someone else can confirm I'm happy to create an issue over on GIT...

Thanks!

James