This via SupermanHomepage: MTV.com asked Superman Returns actors James Marsden and Frank Langella about the sequel and how JLA will affect it.

Apparently the last people we should have asked were the actors involved.

"I know nothing. I saw one article about 'Justice League' being made, and I thought well, how's that going to affect the future of [Superman]?" James Marsden, who played Richard White in Bryan Singer's "Superman Returns" confessed to MTV News. "So I have no idea. I really don't."

Ok, fine. If Marsden couldn't give up the goods we thought maybe his on-screen dad UNCLE could - being a fellow journalist and all for "The Daily Planet." So Mr. Perry White - will there be another Bryan Singer "Superman"?

"I have no doubt it will happen again. I just don’t think it will happen soon," Frank Langella said.

"I thought the first one was a beautiful film. I thought the concept was staggering. It got criticized for not being the kind of Superman everybody expects but Jesus!" Langella continued. "[But that said] I had dinner with Bryan a couple months ago and he said he wants to do the next one shorter, tighter, and with a lot more action in it."

And IESB.net continues to report the JLA movie cast will be announced this week and that the strike will not delay the production:

The WGA is not slowing down the WB and its plan to get Justice League on track, WB sources tell IESB that the cast will be announced this week.

Variety reported that there may be some delays on some studio tent poles including Justice League, this is not accurate according to WB sources.

They tell the IESB that unlike the story ran by the trades, casting is 100% locked. The cast has been chosen and sworn to secrecy but official confirmation will happen sometime this week.

Well, IESB seems to be the only insider source for JLA these days. No other website has posted similar news regarding the announcement that's supposedly happening this week. It might happen by Sunday Nov 18 at the Wizard World Texas convention (it's from Nov 16-18). I've read some WB execs will be attending it.
The Nov 18 rumour actually started on CountingDown via their female insider Emi. We'll see if she was right all along!

The funny coincidence is Scott Porter will be signing autographs at the convention as well. He was one of the rumoured actors for the JLA Superman. Whoo, boy. ;) Hey, worth a chuckle!

Langella dined with Singer 2 months ago. That would be September then. If you remember, September was the month we got the news Singer's sequel will be "postponed indefinitely" and that JLA will start shooting in February and will be filming at Fox Studios in Sydney. Also, casting for minor roles began and rumours about potential actors were getting really juicy (Welling for Superman, Jessica Biel for Wonder Woman, etc). It was the month where it all REALLY started: JLA was moving forward, it was happening. The rumour mill was in full gear. At the same time we got the first news in months that Man of Steel is getting postponed.

So, around this time Singer and Langella chatted about the sequel. JLA was already happening, so Singer knew about it. I'm sure he has heard about the rumours, if nothing else.

This gives me a little hope because Langella and Marsden may only be stars in the movie who don't know what's going on and when the next movie will be but Singer's the director. 2 months ago MOS was still on the table. Let's hope nothing has changed Singer's (or WB's, they're in charge) mind in the meantime.

All in all, the quote "I have no doubt it will happen again. I just don’t think it will happen soon!" sounds kind of depressing to fans who've been waiting for so long for some actual news (or a release date). SIGH. Define "soon". He's talking like it'll take years!