The English working title for the third expansion pack has been revealed. Member Celadus at Sims2Community has posted a copy of the insert that comes with Nightlife in this thread. On it, the title "Sims Open for Business" is mentioned. It's also noted that it's still a working title and thus might change. Besides that, as seen on previous Swiss inserts, the Sims 2 for Mobile is also mentioned on the insert which you can see below. The description for the third expansion is as follows:

"The Sims 2 Open for Business is coming your way early 2006. Create shops, boutiques, entertainment hot spots, home businesses, and more. Hire friendly workers and fire slackers as you strive to keep up with the demand. Get ready to take your Sims from rags to riches."

With the 6-month release interval in mind, Open for Business can be expected some time during the first quarter of 2006, but that hasn't been confirmed yet, naturally. We will keep you updated with new info as we get it.