The best place to go right now is Trac's roadmap: http://trac.elgg.org/roadmap  This shows ETAs and planned features and bugfixes.

Yeah I know this is a bit technical, and I do plan to create an official "less techy" roadmap from this data, but I simply haven't had the time to go through trac and duplicate the more important items to a separate page.  

Here is the official roadmap http://elgg.org/roadmap.php but as @brett mentioned, Trac is really the best place to find out what is coming up.

Brett, you forgot own answer in my theme, which can be better iteration, than Trac

I hope this doesn't sound 'off' topic, but I had hopes that people would begin modding or fixing the current modules and plugins to work with the 'latest' version of the software.    Right now, we have at least three active versions,  1.5, 1.6, and 1.7 - with modules being fixed or updated for version 1.5 when version 1.7.1 is the latest.

I realize the core software has no control over who is doing what or writing what, but take a look at the three lists available on this site..  many are still carrying a 'uploaded' (more than a year ago) number of days and 'updated' within the past few months.. however, updated for version 1.5 or 1.6 - narry to work on 1.7.. and here we are talking about introducing version 1.8.

@Edward, most of the plugins out there have updated, pay no attention to the time it was originally updated, You will see most of the plugins have updated versions on most popular plugins.

For instance, if you click on kevin Jardines Event Calendar you will see on the left hand side a section called releases. Many Releases for may different builds. This is a standard with a lot of the plugins.

Before the 1.8 release I will address the stagnant plugin issue.  The solution will be a combination of stricter rules about hosted plugins and a better plugin area generally.  This doesn't address the problem with authors abandoning plugins, however...

@chambo67,  thank you, yes.. I see that the Event Calendar (one of my favorites) was updated 70 plus days ago (sometime before 1.7) - and in the summary it says that it's for Elgg 1.5 or higher,  and this is helpful, but misleading.   If that summary was written before 1.7 was released it leads one to believe it would work with 1.7,  and even 1.8 (which hasn't been out yet, but 1.7.1 has).. 

I know everyone is trying to make sense out of these plugins, trial and error, etc..  Some even say, "Only to be used on non-production sites as they are in beta.. Heck!. they've been in that stage for over a year now!..

I think it's interesting to note that, "Jomsocial" is now 1.7 beta, working on 1.8 - There is no relationship to these two items of course, except that they are in direct competition for the interest of anyone interested in building a Social Community site..

  One ware, checks the failings of another, applauds their mistakes, and vows their product will surpass the other.  Of course at $149 a pop, JS is lacking right off the bat, and one reason Elgg has such shine!

  I'm mentioning this because I think it's important to the forward development of Elgg to always remember that, "When the bugs and un-fixed plugins, crashes and non-working software  reaches a point where $149, without all that hassle, doesn't look too bad.. People will drift away..   Heck, they won't drift away.. 

  Their Users, and Visitors will DEMAND they shift over to better working stuff!

I think the elgg core team need to have a better relationship with some of the plugin designers. There are some good ones out there.

Here is a scenario ...
I install elgg 1.7.1 and install some plugins that seem to work OK. Elgg moves up to version 1.8 BUT the plugin that you now use on your site will not work on 1.8 but because that plugin is used by a lot of the site users, you are now unable to update to elgg 1.8 until this plugin you use is updated to work with elgg 1.8. YOUR NOW TRAPPED!! The plugin developer vanishes and now I'm in a bit of a bother. Some people are stuck on version 1.5 due to their site core plugins not working with version 1.7.1 and the plugins designers gone AWOL!

We should have the option on www.elgg.org to state which plugins have become a core plugin for our sites. If a plugin recives alot of these votes, elgg core team should look at talking to the plugin designer and working with them. Could have a elgg team core plugin recommendation.

Sometimes, its better to pay for these plugins (Vasco, etc) as you can be more sure as elgg upgrades, so do these plugin's, which goes against the open source of this site maybe ???? Maybe having a standard donation button under all 3rd party plugins, encouging peope to donate for good plugins then encouraging the plugin designers to keep their plugins up to date.

Also some option for every plugin to say exactly what version the plugin is made to work with would be extremely helpful, takes the headache out of broken sites and guess work.

Sad to say, as good as the elgg standard install is, it needs a lot of these 3rd party plugin's to make a community website fun! So the elgg team need to look after these plugin makers.

Looking at the road map ..

http://elgg.org/roadmap.php

It says that there are changes to 

• Profiles
• Revamped interface
• Enhanced River