GGoogle is "allegedly" doing a lot at the moment. They've just "allegedly" announced there is a special event happening next week, where they will "allegedly" announce the Nexus 7, "allegedly" along with the new version of Android, 4.3.
All of those allegations aside, they really have announced that there is going to be an event on the 24th of July, and it's a safe bet that it will involve Chrome and/or Android, due to the fact that it is "breakfast with Sundar Pichai" the head of Android and Chrome.
Software
This one is probably the most likely, as it has been leaking for a fair while, most recently on XDA where Jeff Williams ("allegedly") bought a Nexus 4 on craigslist, and it just happened to be running a pre-release version of Android 4.3. This is awesome, because the tech community then turned this into a system backup and dumped this on the interwebz, available to any Nexus 4 users running TWRP. The changelog seems to be small, and mostly background things, with no groundbreaking new features being released to the forums. However, no Android software update would be complete without...
Hardware
Nexus 7...2...whatever you wanna call it, it's leaked too! TechRadar and Android Central are at odds spec-wise, TR claiming "7-inch LCD display, a 1.2MP camera on the front and a 15MP" against Android Central's "7inch display, 5-megapixel rear camera, a 4,000mAh battery and 4G LTE connectivity...1920x1080 display resolution rumoured..."
Neither party is willing to commit to a CPU choice, with both having solid cases to back them up.
Update- a best buy advertisement has surfaced showing a "new, available Tuesday" nexus 7 available for $229. What that means for Australia is a little less obvious.
Pricing is the usual, $230 for the 16GB and $280 for the 32GB, however here in Aus we're looking at a much bigger price hike due to the much loved Australia Tax.
Engadget received information that stores could be recieving stock on the 20th of July, so it's understandable that hype for the 24th announcement has increased dramatically.
Sources
http://ausdroid.net/2013/07/18/google-event-scheduled-for-24th-july/
Android 4.3
http://ausdroid.net/2013/07/18/android-4-3-now-unofficially-available-for-the-nexus-4/?utm_source=rss&utm_medium=rss&utm_campaign=android-4-3-now-unofficially-available-for-the-nexus-4
http://forum.xda-developers.com/showpost.php?p=43704783&postcount=478
http://www.androidcentral.com/hands-leaked-android-43-rom-google-edition-galaxy-s4
Nexus 7.2
http://www.engadget.com/2013/07/17/new-nexus-7-coming/
http://www.androidcentral.com/next-gen-nexus-7-pictured-tiny-photo-snapdragon-600-cpu-listed
http://www.techradar.com/news/mobile-computing/tablets/take-cover-the-nexus-7-2-is-leaking-all-over-the-place-1166677