Google Gmail v2.3.6 Mod For Android 2.2+
Requirements: ANDROID 2.2+
Overview: This is a modified version of Gmail that fixes the database permissions of Gmail so third party notification widgets (such as Missed It!, Go Notification, and Pure Messenger Widget) can determine which emails are read and which emails are unread for a true unread email count.
a) Your device does not come preinstalled with gmail so the original version can be completely uninstalled first before installing the modified version. After uninstalling original version of Gmail, install modified Gmail.apk as normal by running it.
b) If you have root and your device has Gmail preinstalled in /system/app/Gmail.apk, then you have two choices. Either remove /system/app/Gmail.apk and install the modified version of Gmail normally by running the apk (to /data/app/Gmail.apk) OR replace /system/app/Gmail.apk with the modified version of Gmail. It is probably easier to remove Gmail.apk from the system partition and install it as a normal user application in /data/app/. However you want to do it..Gmail will install as a system or data application. To save space, I would not have it installed in both places.
Note: To simplify the installation of Gmail to the system partition for S-ON devices, I have added Gmail in a recovery flashable zip file format. This method requires busybox to be installed on your device. Make sure you uninstall any Gmail updates first, if possible. This method is only recommended if you have Gmail preinstalled to /system/app/Gmail.apk and you want to replace it with the modified version.
Note: After initially replacing or reinstalling Gmail with the modfied version, the notification widget (ie; Go Notification, Missed It!, or Pure Messenger Widget) needs to be reinstalled to regain premissions.
Note: Gmail 2.x is for Gingerbread. Gmail 3.x is for Honeycomb. Gmail 4.x is for ICS (but version 4.0.1 and 4.0.2 are reported working in Honeycomb too). At the time of this writing, ICS and Honeycomb support is limited. AFAIK, Pure Messenger Widget is the only third party notification widget that supports the ICS/Honeycomb Gmail protocol. Hopefully, more third party notification widgets will add support for ICS/Honeycomb in the future.
Updating from previous modified version of Gmail:
If you already have an older modified version of Gmail installed, the newer modified version of Gmail can be installed on top to perform the update. No need to remove the previously installed modified version of Gmail first.
What’s in this version:
Android 3.2 (Honeycomb) users get the Android Gmail 4.0 (ICS) experience with:
Swipe to move between newer and older conversations
Tap your account to access Recent labels
Set custom notifications for individual labels
Sync last 30 days of messages so you can read and search messages faster both online and offline.
Android 2.2 (Froyo) and 2.3 (Gingerbread) users get:
New Labels API for 3rd-party app developers
Credits to Tsjoklat